J-SMITH69

+1

Slo_crx1

Ehh, even Evo's have their issues. How about junk hardware that breaks like old Nissan hardware for starters? Funky part-throttle transitioning that tends to buck at times, 22mpg at it's best, breaking transfer cases like glass, destroying stock clutches in less than 20k miles, the overly-sensitive maf sensor that tries to stall the car when a Harley pulls up next to you...the list goes on. The WRX's downfalls pretty much stay with stupid stuff, other than being under-powered from their way-too-small turbo and cracking pistons and sometimes sleeves at the 350whp range unless you build the EJ20's.
And personally I wouldn't even bother with the Cobb access port...way over-priced for what it is. EcuFlash is king when it comes to Subaru tuning, and the most you have to invest in is the Tactrix cable which allows you to datalog from the obd2 port as well.

green91

The post cat oxygen sensor doesnt affect engine air/fuel ratio, its sole purpose is to determine the length of time your catalytic converter can store oxygen, so using an anti-fouler wont affect your fuel mileage at all.