So I'm running a Skunk2 Megapower on my S2K right now and want to buy a Berk High-Flow Cat. It comes in 2 sizes, a 63.5 mm or a 70 mm. I'm pretty sure I should go with the 70 mm but I'm not exactly sure. I know the piping on the Megapower is 70 mm. Does that mean the two have to match? What size do I need?! Thanks.

 

63.5mm is similar to the OEM cat, so it'll improve flow just because it's more porous. 70mm is bigger and matches your cat-back, so it'll improve flow even more than the 63.5mm. I think somebody made a thread showing dyno comparisons of the cats.

But... Be prepared for some serious loudness. I had that combo before and it was like having noise cannons behind the car. HFC makes the exhaust deeper and much louder.

 

what year s2000 do you have? I have an 02, and i used to run a full 70mm exhaust, berk header, and berk HFC, with skunk2 megapower duals. I ended up trading the HFC for a test pipe because the HFC makes interior reverberation absolutely awful inside the car. The test pipe made it a little louder, but it goes straight out the back of the car. If you have a year that can run a TP without setting off the CEL, i would get the test pipe...

 

Always match youre HFC or test pipe size to your exhaust for the best results. I also agree with them above.

 

is the interior reverberation with a berk HFC that bad? I guess i might as well get a test pipe then. I just dont want my exhaust to be dumb loud i have a mugen header and exhaust

 

HFC just makes the exhaust deeper and meaner, and magnifies the volume of whatever you already have. 10% increase to OEM is nothing. 10% increase to skunk2 is noticeable.

 

I would go HFC sounds better and not as loud or smelly as a testpipe from my experiences running both on my Ap1

 

How about 70mm berk HFC with 70mm Invidia Q300 dual? Will it kill my passenger (my fiance) when I am cruising (say below 3000-3500 rpm)? I still want to be able to listen to my music when alone and/or talk to my fiance when I am driving (either with top down or top up).

Any feedbacks would be appreciated