My turboed H22 is operating with a 2.5" downpipe to a 3 inches of custom piping to a 3" inlet Magnaflow exhaust. I also have a 3" flex pipe and 3" inlet cat. Is my cat hurting or helping my performance. The reason I put it on was because I didn't want the exhaust to sound really loud and to limit the amount of carbon coming out the exhaust from running rich. I also figured that it would be good for backpressure. But now that it's on, I'm wondering if it hurting or helping. Anybody got any experience on this?

 

You have the same exact exhaust set-up as I do. Im sure with the cat there is only minimal loss, maybe 1 or 2 ponies. Keep the cat, be enviornmentally friendly.

 

Give a hoot, don't pollute.