High Flow Cat/Test Pipe

We may earn a small commission from affiliate links and paid advertisements. Terms

I have a B18c1 and was wondering if a high flow cat/ test pipe would really make that much difference over the stock Cat and if so how much louder are they? Any replies appreciated.


I've had the the head mildly P&P'd multi angle valve job etc. and a CAI


WRX Sellout
You won't see much of a gain, especially on a near-stock or mild setup. On a related note, you won't see much of a difference between a high-flow cat and a test pipe.

I chose a turboback exhaust that had a high-flow cat and a resonator to cut down on noise and so that I could still pass emissions without swapping the stock exhaust back on. IMO, catless exhausts are way too loud, and usually stink pretty bad (this can suck in the summer with your windows down).

If you keep your current setup, keep the stock cat and spend the money elsewhere. You won't notice any gain from it.


Senior Member
:werd: on the too loud and stink. i have full manderl bent exhaust with no cat, i have to shift early accelerate very slow so i dont attract the cops(btw my car looks beat up; no gloss, slow, etc. so i dont like the added attention).


Super Moderator
mine really wasnt that much louder. but i used one of those ebay obx ones. its not just a pipe, its straight though but it has some baffling on the inside so that might help with noise.