after some search I couldn't find anything about it, except one person asked about it, but didn't get a response...

so I'm wondering if anyone know if there is a different between a sti up pipe and a gutted wrx, does the sti have a different diametere? Thanks in advance.

 

the oem uppipe in the wrx has a catalytic converter in it which MASSIVELY blocks airflow. Other than the fact that the STi uppipe comes with no cat in it, they are the same...fitment, looks, heatsheild

when installing my turboback, me and my buddy removed the uppipe and drilled and honed out the cat. great free mod if you have the tools, time, and patience

 

The STi uppipe is notorious for having crappy welds on the heat shield, so after a while the heat shield will start to vibrate. If you get an STi uppipe take the extra step and have it welded up at an exhaust shop before you install it to avoid any future problems.

IMO...its better to get an aftermarket uppipe and save yourself the hassle. The aftermarket ones flow better as well.

 

did you search over in NASIOC? i know that this topic has been covered before over there....


i can't refute the ease of getting an aftermarket pipe...it is much easier. however, from dyno tests, a gutted WRX uppipe works just as well as an aftermarket uppipe.