I want to get rid of the gas exhaust smell by installing a hiflo cat. my car runs a 3 inch straight pipe back to the catback. i am looking at getting the magnflow metallic cat. it worked great on my last fd.my question is should i get the one that is more round in shape,or shaped more like the stock one?I know its going to hurt my hp a little ,but with the last dyno was 443 whp at 14 lbs of boost with a average tune,i think a great tune with the cat should net me around the same hp.

 

I don't think the restriction will be a problem, just remember to get the tune right after you install it, excessively rich conditions will kill a cat. I would defiantly stick with the 3" and you may want to check out Random Technologies.