Deciding between Cobb Tunning's Accessport and Open Source Tuning
One of the hardest decisions when modifying your WRX or STI is whether or not to use cobb accessport or open source tuning. The stock tune for a wrx or STi leaves some power on the table but when the restrictive down pipe and cat back are replaced there is even more power left on the table. Each of these engine management options has positives and negatives. First lets look at the accessport.
The accesport is priced locked at 595 and used ones go for 500. If you shop around you can find vendors on NASIOC giving away stuff with an accessport to entice the deal a little. Included are two off the shelf maps stage 1 and stage 2. 91 octane maps and a few other maps can be downloaded as well from cobb tunings site for free. These maps are great for owners who are do not live near a reputable Subaru tuner or who do not plan on modifying past stage two and want a set and forget it approach.
The cobb accessport also has a nifty little boost gauge and shows some other parameters too. However these gauges are what the ECU sees and may be in accurate compared to a real dedicated gauge.
Open source tuning is more complicated. For the technology challenged it is definitely not recommended.You need a tactrix cable ECU Flash and Romraider. You also MUST have a boost gauge and a Wide-band gauge if you plan on tuning the car yourself. If you plan on bringing the WRX to a dyno where a reputable tuner is then I think you could get by with just a boost gauge. I would only recommend going open source if you contact your tuner and you are having it dyno tuned.
Tuning on the street is illegal because of the speed you have to reach to do a proper log. Most e-tuning services require a log of your car doing a third gear pull which puts you in excess of the speed limit.If you are going to go open source be sure you have a laptop that is capable of flashing the ecu map in case you need to re flash the tune.
I would choose cobb tuning accessport mostly because dyno time is expensive and while a dyno tuned stage 2 is better than an off the shelf map I would rather get a tune after changing the turbo and getting the cobb accessport would save me money in the long run.