the cheap ones all have the same core diameter, just different inlet sizes. magnaflow resonators are pretty good, get one to replace your test pipe. you can also try and get one fo magnaflows duel inlet, duel outlet mufflers and make yourself a twin loop lol..

use your imagination with this piscture

 

anyone know if magnaflow high flow cat is any good. its only like $60 shipped on ebay??

 

if you live somewere were the cops like to snoop under your car like were i live, id gut the cat. it looks stock, and the cops wont know a thing.