what kind of catalytic size should fit on GC?

fujiwara_yingyu · 11-13-2006, 06:17 PM

I am going to change the high flow catalytic. I phoned the muffler supplier. They have 3 inch, two and quarter , and two and half. Which size should work on Gc? Thanks for answering my question

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rs_two_five · 11-13-2006, 09:30 PM

please don't quote me.. but.. I believe the stock cat pipe size is around the 2 1/4 size. But the problem is.. you don't just have one cat, you've got two of them. The first of them coming from the motor has a 90 degree bend within the cat itself, and the second cat (further downstream) is just a straight flow through design. Honistly.. I wouldn't really bother replacing your cats, cause you'll loose quite a bit of bottom end torque which as all us 2.5RS owners out there know.. thats about the only power we've got..

As for a decent setup, just replace your exhaust header, and the cat-back section.. it helps quite a bit top end, and you still maintain a decent amount of power down low. My setup is Borla Gen2 header with Greddy Evo2 catback and stock catalitic converters, and it sounds bloody awesome, not too loud, and plenty of rumble

Oh and just a note.. if you go equal length header, you'll loose the boxer rumble sound (ie OBX unit) but the borla is unequal length so you actually create a boxer rumble.

11-13-2006, 06:17 PM	#1
fujiwara_yingyu Scooby Specialist Member Sales Rating: (6) Member#: 116351 Join Date: May 2006 Chapter/Region: VIC Location: Richmond Vehicle: 2009 CFRP GR WRB STI 2006 EVO IX MR	what kind of catalytic size should fit on GC? I am going to change the high flow catalytic. I phoned the muffler supplier. They have 3 inch, two and quarter , and two and half. Which size should work on Gc? Thanks for answering my question * Registered users of the site do not see these ads.

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11-13-2006, 09:30 PM	#2
rs_two_five Scooby Specialist Member Sales Rating: (7) Member#: 99206 Join Date: Oct 2005 Chapter/Region: W. Canada Location: Cold Lake, Alberta, Canada Vehicle: 2007 WRX wagon 02C	please don't quote me.. but.. I believe the stock cat pipe size is around the 2 1/4 size. But the problem is.. you don't just have one cat, you've got two of them. The first of them coming from the motor has a 90 degree bend within the cat itself, and the second cat (further downstream) is just a straight flow through design. Honistly.. I wouldn't really bother replacing your cats, cause you'll loose quite a bit of bottom end torque which as all us 2.5RS owners out there know.. thats about the only power we've got.. As for a decent setup, just replace your exhaust header, and the cat-back section.. it helps quite a bit top end, and you still maintain a decent amount of power down low. My setup is Borla Gen2 header with Greddy Evo2 catback and stock catalitic converters, and it sounds bloody awesome, not too loud, and plenty of rumble Oh and just a note.. if you go equal length header, you'll loose the boxer rumble sound (ie OBX unit) but the borla is unequal length so you actually create a boxer rumble.