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Seeking guidance with my first attemp at tuning my car

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Hi, guys

I am preparing to attempt tuning my stock JDM 2008 S-gt /WRX and I would appreciate any guidance you guys can provide. I will be using a Tactrix unit and ECU flash to conduct the tuning. I know it’s advisable to have knock detection equipment and I am working on getting a unit, I am seeking assistance on the best way to go about this project. Below is a list of the modifications that have been made to the car.


1. Perrin replacement filter

2. Processwest TMIC

3. AME Water meth kit

4. Grimmspeed 3 port boost control solenoid

5. Turbo: Twin scroll Tomioka TD06 20G

6. STI Headers and up pipe

7. Tomioka 3’’ down pipe

8. Greddy axel back exhaust 2.8’’

9. Dual core radiator

10. Exidy Stage 1 clutch

11. GBF response hybrid BOV

Additionally a wide band and boost gauge are installed, I was told I will need to upgrade the fuel pump and injectors as well but I am not sure which ones to purchase for my model car.

Please keep in mind these mods were not planed, but were done to solve a problem.

(Back story)

The turbo was assessed to have failed and at the time and based on my location (Caribbean) the above mention turbo was easily available, by purchasing this turbo set off a chain reaction of modifications. Currently the car is what I believe to be in a reduced boost or aspirated state, as the car is slow and doesn’t respond like when I first got it. I will be sure when I hook up the Tacktrix cable and look at the information. My intention is to get the car running safely as possible while bring the car back to life.

The very first step I'd suggest (if you haven't already) is to purchase the Practical Reflashing course. This is essential information for anyone reflashing a stock ECU. While it's not 100% identical, the worked example on the supercharged Toyota 86 will be quite helpful when it comes to tuning your Subaru WRX as the ECUs are very similar in their operation.

The Subaru ECU has a reasonably sophisticated knock control strategy but I always suggest confirming that it's operating correctly using audio knock detection equipment. Scanning/logging is an essential aspect of reflashing any ECU so that you can see what was happening and where. If you are going to change injectors then you will also need to rescale the tune to suit these too. Again this is covered in the reflashing course. Depending on how modified your intake is, you may need to rescale your MAF sensor too. If it's just a drop in panel filter then this normally won't have too much effect but a full intake kit, pod filter, or a different MAF housing will require the MAF calibration to be adjusted.

Take a look at the course and let me know what specific questions you have.

Thanks Andre, will definitely check out the Re-flashing course. my additional question would be; what boost levels should i aim for based on my list of mods. i have done lots of reading and figure i shouldn't do more then 10 psi until i am built, i also read its possible to have the car run safely if its tuned correctly and conservatively. As for the injector , what would be the your or anyone who have worked on JDM WRX recommendations. My friend tried a Walbro 255 in-tank replacement fuel pump on the same type car and it stopped working after two days, we are not sure why but after the stock was put in car was normal again. my aim is to reach 300BPH and no further.

any advice will be greatly appreciated.

Based on you saying that the car feels slow, I would look out for mechanical issues before tackling the tuning. Check for boost leaks, pre-turbo exhaust leaks, wastegate not completely shut etc. Your boost may also be set lower than previously, which will affect how the car feels, but with the mods it has I would expect it to feel just as fast if not faster even on the factory tune.

I expect ultimately you will want to and be able to run more than 10 psi safely but start out slowly.

Hi HS,

Thanks for your suggestions and i will make them part of my pre-tuning checks, and your right i do believe the boost level has been reduced for safety. like i stated in my intro, my reason for taking this course is due to the waiting period for the top tuner in my island. i figured ill learn and become an option for others. I am currently in Jamaica, can you suggest any places i can pick up any tuning equipment or other after-market goodies i can pick up before i head home. looking to pick up the right after-market fuel pump for my ride. you could whatsapp if you like @ 1 246 234 4891

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