turboDXcoupe

its federal law to keep catalytic converters on just get a high flow cat and safe the dtress of a fat *** ticket and possibaly impouned car...or get a test pipe

bumblezc

Made the good ol' Y-pipe with a block of plate. Just two bolt and it is an open DP. You can by them but my 50 year old welder, 8 dollar exhaust flange and some scrape metal works great. Looks like ---- but my car is so low you never see it.

HMT-Admin

because test pipes are legal?

2.5 will be fine for your setup, and ditch the cat..

street_kings

get an old truck cat, gut the bitch, and weld it over your test pipe so it looks like a cat if you're that worried about it.

quadnie

2.5 inch will work, go for mandrel bends.

On the cat, yeah you can go find yourself a nice overpriced high flow race cat and get that installed and live it the legal way (even though the odds are against you still when passing inspection). Or just buy a spare cat that would mount to it's size, gut it, weld a pipe inside the cat so it's essentially a "test pipe" OEM cat.

Yeah, I thought just gutting it and slapping it back on was the best way, but you actually create back pressue with the exhaust gasses expanding in the chamber, and probably some audible difference. The proper way to do it is to take a section of exhaust pipe that fits the space perfectly and weld it in. Be sure to fully seal the pipe to prevent any whistling.