I just got my Si and was installing my Greddy EVO II, I noticed the cat was broken so I need a replacement. Any recommendations (Carsound, EVO)? Do I need a 2.25 or 2.5 Cat?

 

U need a 2.25 inch cat. I would just run a test pipe ($20 ebay cat) or get one custom made. I have a jackson racing hi-flow cat and its alrite.

 

If you're NA don't get a testpipe. It's bad for low-end.

If anything get a high-flow. Flowmaster also makes them.

 

carsound is a decent cat to use. i noticed your in florida.. so i google'd to see if fl had emissions & smog.. they do, so if you run a ebay testpipe suggested above.. then i hope you know someone to slide your car threw emissions otherwise you will NOT pass the NOx & CO count on your cars emissions will be waaaaay to high, just thought thou. carsound is a good, smog'able cat, not to expensive either. anyway carsound is the way to go imo.

 

get unversal and have your local muffler shop weld flanges on it... or if you have a welder just weld them yourself... universal cat = $50.... flanged cat specific to your car=$150+

you can get flanges cheap and if you need to extend the cat, you can weld an extension pipe to fit the "cat space"