Copyright MRT Performance Pty Ltd 2004 www.MRTrally.com.au 1/12 Revised 22 Feb 2007 Impreza MY99-MY05 2.0L

MRT Performance Pty Ltd ACN : 100 017 543 1 Averill St. Rhodes NSW Sydney AUSTRALIA 2138 Phone +61 2 9767 4545 Facsimile +61 2 9767 4599 info@MRTRally.com.au www.MRTrally.com.au

Subaru Impreza WRX – MY99-MY05 2.0L THE WRX UPGRADE STORY We all know the problem well – you have finally got your hands on a WRX and after all that time spent reading magazines, advertising and general propaganda, you still have no idea where to start with enhancing the performance of your car. So how do you cut through the clutter and know what you should be doing, or even better, know exactly what you are getting for the money spent? Every day we get many enquiries by clients unsure of where they should be starting, or who have been given conflicting advice on what modifications they should start with. Or more dangerously, told certain things to do which are NOT reliable. A good example would be the fitment of a full exhaust system on a late model STi (MY01 GD on). Some workshops have advertised this as giving a 20kw gain (or more) however this gain is actually due to a savage boost spike in the mid range and is not sustained to higher levels. The actual peak gain is only a couple of kw.

Earlier model WRX’s (MY93-00 models) tend to respond reasonably well to minor modifications that relate to increasing airflow (eg exhaust system, replacement air intake assembly, minor boost increase, etc). However MY01 onwards models will not give you solid gains in performance (no matter what other bolt on modifications you have made) without altering the various ECU parameters the car is running standard (eg fuel, ignition, etc). So what is the best combination of modifications? Easy – read on…

Copyright MRT Performance Pty Ltd 2004 www.MRTrally.com.au 2/12 Revised 22 Feb 2007 Impreza MY99-MY05 2.0L

Testing here has been completed on an MY03 WRX. On earlier model cars (the MY99/00 and MY01/02) similar results are achievable (where the earlier models run lower compression, changes in boost/fuel/ignition timing etc can be used to compensate for similar gains).

DYNO PROVEN POWER

One of the things our new DynaPack 4WD dyno allows us to do (check out the website at http://www.mrtrally.com.au/performance/dynapack.htm for further details) is perform very specific (and

repeatable) testing on any given vehicle. Combined with the lack of variables which normally affect many dyno results (such as wheel spin, differences in gearing, etc) we have been able to narrow down what modifications work best, and in what order they should be undertaken to get the best possible results! The outcomes of our testing are represented in 3 specific kits that we have developed, affectionately known as the range. At all stages we have kept 3 things in mind:

• 1/ Get the best possible performance for WRX owners with maximum safety and reliability. • 2/ Keep cost of the kits to a minimum in relation to the performance increases made, enabling

owners to consider their requirements and identify the kits best suitable for their needs. • 3/ Make the gains easily identifiable, with Dyno proven figures used to verify results in each case.

For the purposes of our testing and research our Workshop Manager Luke (and with the kind permission of his partner Rachael - thanks Rachael!!) kindly volunteered his new MY03 with 7200kms (4500 miles) on board. The results shown are based on this car, however all tuning has been done with safety and repeatability in mind – meaning if we can get it, so will you!

And for those STi owners, there is no need to worry. Similar gains can be had with a specifically developed kit for those models (MY99/00 and MY02/03/04/05). While only the MY03 WRX graphs are shown here, we have seen results upwards of 250kw at the hubs on our Hub Dyno (in 5th gear) with modifications similar to those found in the XB kit (without the need for injector and turbo changes as these are already upgraded on the STi models!). Upgrades are also available for the Liberty GT, Forester XT (ask us for the separate article on the XT Forester Kits, with other articles coming soon) and other models. Simply call us for further details!

Copyright MRT Performance Pty Ltd 2004 www.MRTrally.com.au 3/12 Revised 22 Feb 2007 Impreza MY99-MY05 2.0L

WHICH ECU MODIFICATION WORKS BEST?

Before we get stuck into the kits and results, a quick word on the various ECU modifications out there at present. As mentioned in the initial paragraphs, big gains simply can’t be seen on any late model WRX without alterations to the standard ECU’s control over proceedings. These days there is an absolute plethora of items available to alter the ECU tuning on the WRX, however these can be grouped into three main categories:

1/ Interceptor style units which alter the signal seen by the standard ECU to confuse the decision

logic of the standard ECU, fooling it into changing fuel/ignition/boost settings etc to achieve a given result (eg Unichip, Utec, Exede, etc). 2/ Complete replacement ECU’s which fit in place of the standard JECS OEM ECU. Some fit the standard wiring harness via plug in looms, while others full replace the standard ECU and relevant components of the wiring loom. Often tend to be outside the budgets of many clients and/or have features not needed or used by customers fitting them (eg Motec, Link, Haltech, Autronic, etc). 3/ Retuning the standard ECU (a more recent development) using specially developed software designed solely for that purpose. By far the most useable and flexible software available for this purpose is EcuTeK, for which we are the exclusive Australasian Agents. Any of the 3 above options can often be used to achieve the results similar to what we have done, however we have chosen to use the EcuTeK software primarily due to its flexibility, safety and cost effectiveness. The other key reason for choosing EcuTeK is that it allows adjustment of all factory functions such as active knock control, variable cam control, etc. Many of these functions are not available in many aftermarket ECU’s (with the exception of high end systems such as Motec), and interceptor style units often only allow minimal adjustment of some functions. With our tuning experience combined with the EcuTeK software, changes could be made quickly and easily to all facets of the standard ECU. This allows us to extract the safest possible gains in torque, power and efficiency.

Copyright MRT Performance Pty Ltd 2004 www.MRTrally.com.au 4/12 Revised 22 Feb 2007 Impreza MY99-MY05 2.0L

THE STANDARD CAR Volumes have been written about the WRX in its various forms, so much so that we won’t go into graphic detail here. For those of you who are new to the WRX, or haven’t understood anything we have written to this point, check out the Subaru Performance Handbook of the 3Rd Edition Training WRX book. Information on the book itself can be found on our website at http://www.mrtrally.com.au/performance/wrxbook.htm and you can also follow the links to purchase a copy online if you wish. On the MY03 model that we are using for this comparison, Subaru have made some subtle changes that need to be remembered when comparing it to other models. Firstly, this is an Australian Domestic Market MY03 model, with 165kw at the flywheel standard. It runs a higher compression ratio compared to earlier models (so ignition advance and maximum safe boost levels are restricted slightly in comparison), smallish TD04 turbo (very similar in spec to earlier models) and the same restrictive intake and exhaust setup found on nearly all standard WRX’s. Also note that on the MY03 model, there is NO catalytic converter in the uppipe leading into the turbo as introduced on the MY01/02 models. At all stages a minimum of 3 full power runs were made to ensure the results were repeatable and correct, with average figures quoted in all circumstances below. It was a relatively warm Winters day with a consistent ambient temp inside the Dyno room of 21-23 degC throughout the testing. All runs were made in 4th gear. So what was the baseline performance of the car? Standard the car ran just on an average of 140kw at 6000rpm, 1142Nm of tractive effort at 3900rpm, with peak boost averaging at 15.3 Psi. Post intercooler intake temperatures were consistently 24 degC at start through to 32 degC at the peak power figure.

This worked out to be the base against which all other changes were compared.

Copyright MRT Performance Pty Ltd 2004 www.MRTrally.com.au 5/12 Revised 22 Feb 2007 Impreza MY99-MY05 2.0L

IMPREZA WRX - XA Kit The most common cry that we get is “I want more power but I only get $10 pocket money each week, what can I do?”. The first instinct by many people is to fit a full exhaust to their car in the hopes of instantly unleashing the beast within, only to have had wild boost spikes or little to no noticeable change at all. The problem here is that on the post MY01 models, the Subaru ECU got smart and adjusted accordingly, so bolt on hp became a thing of the past. A well designed turbo back exhaust such as the MRT system is certainly a key component of getting large gains from the car (so don’t fret if you have already fitted one!), but there are other areas that give better results at these early stages. Obviously without changing the ECU settings, you won’t get far no matter what you do, but changing the ECU and not allowing the engine to breath more easily won’t get you far either! With that in mind the following combination was shown to give the best bang for buck:

~ 3” rear muffler from the rear diff back (using an adaptor flange to bolt up to the standard rear flange with no alterations).

~ Replacement reusable foam filter element inside the standard air box. ~ Removal of the resonant air box inside the inner guard to remove restriction to airflow entering the

standard air box. ~ Base level retune of the standard ECU using EcuTeK Type 1 base map, with peak boost of only

15.9 Psi (remembering standard boost on this car was 15.3 Psi).

The results speak for themselves with up to a 22% gain in torque and a gain of over 28kw at the wheels, and NO losses in performance ANYWHERE through the rev range. This was also all done with only a 0.6 Psi increase in boost!! On the road the car felt just as strong with drivability far improved over the standard car, and mid range performance noticeably improved (especially when overtaking!). ☺

Whilst the tune level was VERY safe for day-to-day use with no signs of detonation at all (using 98 RON Shell Optimax pump fuel) it was decided to detune things slightly to make it absolutely bulletproof (read race use on a 40 degC day). Playing with fuel and ignition timing a little, power gains in this level of kit were still over 20kw at the wheels with little change in on road behavior from the hypo example first produced. That is more power, more economy, better drivability and above all, more safety than bolting on an exhaust system which would have cost over AU$400 MORE fitted! And don’t worry, it gets better from here…!

Copyright MRT Performance Pty Ltd 2004 www.MRTrally.com.au 6/12 Revised 22 Feb 2007 Impreza MY99-MY05 2.0L

IMPREZA WRX - XB Kit With the basics in place, now it is time to turn up the wick a little. The key to any high performing four cylinder turbo engine is airflow, and lots of it. With that in mind, the next steps revolve around removing restriction in the exhaust and intake side of things further. With the MY03 WRX, for some unknown reason Subaru also decided to go back to smaller 380cc injectors and a lower spec fuel pump compared to earlier models. With this level of upgrade taking the standard setup to its limits, with safety in mind changes to the standard fuel system are also required. Changes for the XB Kit include:

~ Upgrade from MRT rear muffler only to full 3 inch MRT exhaust system from the turbo back, including custom dump pipe with splitter for improved response, and hi flow cat converter (either placed under the floor in the center pipe for peak hp gains OR standard location to comply with EPA guidelines).

~ Upgrade foam flat panel filter to alloy cold air pipe, which replaces the standard airbox and places a

foam filter element inside the inner guard for easier breathing and as much cool air as it can get. ~ Upgrade standard fuel pump to higher spec 400hp in tank replacement (fits OEM position). ~ Upgrade EcuTeK Level 1 tune to EcuTeK Level 1.5 (which increases peak boost to 16.5 Psi)

Copyright MRT Performance Pty Ltd 2004 www.MRTrally.com.au 7/12 Revised 22 Feb 2007 Impreza MY99-MY05 2.0L

With the ability to flow a much larger amount of air, the WRX is now really starting to come alive. The cold air intake replacement and full exhaust system have lead to a dramatic reduction in turbo lag, with the car now proving to be incredibly responsive throughout the rev range. This culminates in a peak power gain of over 40kw at the wheels more than the standard car, and a torque curve flatter than the Salt Lakes! And before you ask…this IS the bulletproof tune! Peak boost pressures are only 16.5 Psi (less than 1.5 Psi higher than the standard car!). The main differences come in the ability to ensure that the car is running perfect fuel/air mixtures at all stages throughout the rev range. Fitting the above modifications WITHOUT any form of ECU tuning would result in less improvement than the Type XA kit!

An added bonus with this level of modification has been the improved fuel efficiency. When not taking advantage of what has now become a seriously quick car, economy actually improves due to the more accurate mixtures being run AND the engine being able to breath more easily. It is highly unlikely you will find a guaranteed and reliable 40kw at the wheels improvement ANYWHERE else in the world at this cost (refer last page for full details on pricing)! The closest comparison is a well known rival kit for the MY01 onwards models at over AU$600 more which only promotes a 30kw gain!

While intake temperatures on these runs proved relatively stable (peaking at 34 degC) it had now become apparent that we were reaching the limits of several standard components. The injector duty cycle was now up to around 87% and it was becoming obvious that no matter how hard it tried the standard TD04 turbo was simply at its limits of efficiency. On the road this also showed above 6000rpm, with the car losing urge noticeably. But of course there are easy fixes to these… ☺

Copyright MRT Performance Pty Ltd 2004 www.MRTrally.com.au 8/12 Revised 22 Feb 2007 Impreza MY99-MY05 2.0L

IMPREZA WRX - XC Kit The next round of modifications centres around sorting out the deficiencies that became apparent in the testing of the XB kit, namely fuel supply and turbo efficiency. Along with the full exhaust system, cold air intake, 400hp fuel pump and EcuTeK 1.5 tune, this next stage includes:

~ Upgrade to STi MY01 RA injectors (550cc in size, compared to 380cc standard).

~ Upgrade to VF30 turbocharger (although more recently we have been using the VF34 for slightly reduced lag now that they have come down in price!)

~ Upgrade to EcuTeK Type 2 level of tune (with boost increase to 17 Psi).

Fitting the VF30 to the car has certainly led to a noticeable gain in peak power, with figures now rising to 197kw at the wheels. While turbo lag has been brought back to standard MY03 levels (not at all bad given the dramatic increase in turbo size for what is still basically a standard car with a couple of bolt on modifications), it doesn’t drive poorly on the road compared to the XB Kit as it might suggest. Once the car hits mid range at around 2700rpm it takes off with no drop in urgency right through to the redline. Fitment of the larger injectors has also kept injector duty cycles down, with plenty of safety margin built in. Air/fuel ratios are also well within limits, with the car able to run at this level all day. Note that boost levels have been kept very safe at a maximum of only 17 Psi. Any higher boost levels and we recommend forged pistons and rods. With the volume of air now passing through the standard intercooler, it was looking like that would be next on the list of things to do. Intake temps were now peaking at 38 degC (ambient temp still 21 degC in dyno room).

Copyright MRT Performance Pty Ltd 2004 www.MRTrally.com.au 9/12 Revised 22 Feb 2007 Impreza MY99-MY05 2.0L

From other dyno testing we have done, this gives you around 25kw more at the wheels than an Australian Domestic Market STi (170kw at the wheels standard on our dyno in similar conditions) but well over $10K less in purchase cost!! ☺ At this level, there are only a couple more things that can be changed without considering the next major step up into stronger engine internals (in order to sustain higher boost pressures). For owners with big hp goals there are no other alternatives – if this is you then let us know so we can set a plan of attack from the start. Normally such ventures end with a 2.5L short motor (from the US Spec STi) and variations on that theme. Other options also include a 2.2L or 2.4L stroker conversion using forged pistons, rods, strengthened stroker crank, head studs, etc. At this level we normally build an engine to suit client’s requirements, and gearbox strength also becomes an issue that needs to be addressed.

SO WHAT’S NEXT? So now what I hear you ask – you have come all this way and there are still a couple of hours left in the day. Despite protests from some of the guys that the fridge had run out of beer, there just so happened to be a couple of other items which we had lying around to throw on there for interests sake. Our current 3-inch muffler design has served us well over the years, proving to be exceptionally quiet (one of the quietest on the market) yet providing strong gains in exhaust flow over the standard item. More recently we released a Cannon muffler with 4-inch tip for those owners wanting the maximum possible performance with little regard to noise levels. Or alternatively, the best possible note from the car, which just so happened to flow as much as possible as well – it all depends on your point of view! In a straight out comparison, with NO other ECU tuning whatsoever, the results surprised us:

As the graph shows, the additional flow provided by the larger rear muffler provided gains in power above 5500rpm, and also helped reduce turbo lag marginally. On the road the muffler felt like it was worth 30kw, but it probably had something to do with the noticeable increase in exhaust note! For clients not wanting to attract too much attention and wanting to keep things as quiet as possible, it would be better to sacrifice a little hp for the quieter muffler.

Copyright MRT Performance Pty Ltd 2004 www.MRTrally.com.au 10/12 Revised 22 Feb 2007 Impreza MY99-MY05 2.0L

We can alternate between the two muffler choices as a no cost option in the Upgrades range for any client wishing to change. We wouldn’t expect the Cannon muffler to make anywhere near the difference on the other two kits as with the smaller turbo they do not have the same air flow requirements at peak rpm as this setup running the larger VF30 turbo.

HEY GUYS, WHAT ABOUT THIS INTERCOOLER OVER HERE? With the free flowing rear muffler fitted, the most obvious thing holding back power was the standard top mounted intercooler. As noted previously, post intercooler intake temps were ending up around 38 degC (17 degC over ambient) towards the end of each run, and there were also questions over its ability to flow the levels of air we were now asking of it.

We knew it would be good, but not that good! With no change in peak boost level (still max 17 Psi), temps under control, and only 5 minutes additional tuning over the

XC kit, we picked up a further 12kw at the wheels!! This was on top of the gains seen with the Cannon muffler. We were now up to 80kw at the wheels (that’s 57%) gain over the standard car, in what is a very streetable AND reliable package. In fact your Grandma could drive this to the shops and think it was an otherwise standard car without the increase in exhaust note!

The funny thing is that as the intercooler tested was actually the smaller Mk1 model from the earlier MY01/02 model, which has since been updated to a larger more efficient item! We would expect there to be another kW or two found in the newer version, we just didn’t have one handy at the time! And the best news? If you feel the need to reach this level of performance, it will only set you back the cost of the Level Three kit and around AU$1470 including GST (depending on year model car) for a replacement top mounted intercooler with Silicone Y Pipe. And on that note, with Luke keen to get his car back and the guys content with a couple of days solid work, it was time to go and restock the fridge. ☺ NOTE Whilst this story was completed on a 2003 WRX, other kits are available for the STi, Forester GT, Liberty GT etc. For a kit to suit your car, please contact MRT Performance

Copyright MRT Performance Pty Ltd 2004 www.MRTrally.com.au 11/12 Revised 22 Feb 2007 Impreza MY99-MY05 2.0L

FREQUENTLY ASKED QUESTIONS Do the modifications void my new car warranty? One of the most common queries we get in relation to performance upgrades on new models is the potential effects on factory warranty. To that extent, Subaru retains the right to refuse claims on warranty where the item being claimed on has been modified or changed from factory specification. However, to date we are yet to have any vehicle fitted with one of the MRT Power Kit upgrades fail as a direct result of the improvements made, with hundreds of kits supplied and fitted to date Australia wide. We also offer a full 12 mth warranty against manufacturer defect on all parts we supply. We also spend countless hours on research and development of parts, tuning, and the associated effects of these changes on the rest of the vehicle. If I have one type of kit, can I upgrade at a later stage if I want more? Easily! All of our parts are designed to be compatible with other items. For example if you have the XA kit, upgrading to the XB kit consists of adding a new engine and centre pipe to the muffler you already have on the car, adding the cold air intake and retuning the ECU accordingly. The cost to upgrade depends on what parts you already have fitted. As a guide it’s generally around the difference in price between your kit and the next + any additional labour associated with the changeover that isn’t covered in the kit. How long does the work take? Both the XA and XB kits can be completed within 1 day. The XC kit requires 1½ days due to the considerable amount of parts requiring fitment. When booking your car with us (or your local authorised outlet) the total time your vehicle is required will be reconfirmed for you as well. I have already made some modifications, can I get the same results as seen above? A lot of customers perform modifications in stages, partly due to budget constraints and partly because it starts in stages and then the bug bites and performance becomes an obsession. All of the modifications listed above can be performed around what you already have. Depending on the quality and type of items fitted, we will get performance gains as close as feasible to the above. Of course to make sure you get the gains the vehicle is capable of, just make sure you use MRT parts from the beginning! ☺ Where can I get the work done? Any authorised MRT/EcuTek reseller can easily complete the above work for you, or assist in designing a series of modifications around your requirements. For further information and contact details please check out our website at http://www.mrtrally.com.au/performance/dealers.htm. Of course if you have any other queries that we have missed, or need further information either give us a call directly at our new premises on (02) 9767 4545 or get in touch with your local reseller.

Copyright MRT Performance Pty Ltd 2004 www.MRTrally.com.au 12/12 Revised 22 Feb 2007 Impreza MY99-MY05 2.0L

PRICING AND INCLUSIONS – Subaru Impreza WRX MY99-MY05 2.0L * Whilst realistic and achievable on all WRX models, power gains quoted are subject to 10% variation as a result of fuel quality and temperature variations in various areas of Australia. If you have concerns about any aspect of the work to be completed, please just ask us (or your local Authorised MRT Distributor). ** Refer dyno data in XA Kit body of this document.

XA kit *Guaranteed minimum 20kW ATW gain

(up to 22% more torque) Includes: 1 x MRT 3” Rear muffler (Cannon muffler available as no cost option) 1 x Adaptor Flange for fitting to standard exhaust flange at rear diff 1 x Flat Panel Foam filter 1 x EcuTeK MRT ECU Type 1 software upgrade

1 x EcuTeK Certificate of Authenticity 1 x Factory Warranty Guarantee

1 x Intake resonatorectomy 1 x Recalibration of factory ECU using mapping extensively developed on road and dyno ** All labour to fit/tune/test vehicle

For pricing and more details refer to your local MRT supplier

XB kit *Guaranteed minimum 40kW ATW gain

(up to 30% more torque) Includes: 1 x MRT 3” Rear muffler (Cannon muffler available as no cost option) 1 x MRT Centre pipe with high flow cat and centre resonator (or cat available in engine pipe instead) 1 x MRT Engine pipe with splitter on turbo outlet for improved response 1 x 500hp in tank fuel pump replacement 1 x MRT Cold Air Intake pipe with filter (your choice of K&N or Unifilter filter element) 1 x EcuTeK MRT ECU Type 1.5 software upgrade

1 x EcuTeK Certificate of Authenticity 1 x Factory Warranty Guarantee

1 x Intake resonatorectomy 1 x Recalibration of factory ECU using mapping extensively developed on road and dyno ** All labour to fit/tune/test/vehicle

For pricing and more details refer to your local MRT supplier

XC kit *Guaranteed minimum 55kw ATW gain

(up to 40% more torque) Includes: 1 x MRT 3” Rear muffler (Cannon muffler available as no cost option) 1 x MRT Center pipe with high flow cat and centre resonator (or cat available in engine pipe instead) 1 x MRT Engine pipe with splitter on turbo outlet for improved response 1 x MRT Cold Air Intake pipe with filter (your choice of K&N or Unifilter filter element) 1 x 500hp in tank fuel pump replacement 1 x MRT billet fuel rails

1 x additional fuel pressure regulator 4 x 530cc replacement fuel injectors 1 x VF30 Turbocharger (or VF34 available as no cost option) 1 x EcuTeK MRT ECU Type 2 software upgrade

1 x EcuTeK Certificate of Authenticity 1 x Factory Warranty Guarantee

1 x Intake resonatorectomy 1 x Recalibration of factory ECU using mapping extensively developed on road and dyno ** All labour to fit/tune/test/vehicle

For pricing and more details refer to your local MRT supplier