[GTJim]

The rule of thumb on the Cobra's is that if you go with an X-pipe (as opposed to an H-pipe) you want a flow-through type muffler like a Dynomax Ultra-Flo or a MagnaFlow. If you go with an H-pipe, then you should use a chambered type muffler such as the Flowmasters. If you mix the two, people say it sounds shi**y.

The H-pipe combo has a deeper sound, but makes a few less ponies. The X-pipe combo has a little bit higher pitch sound, but still sounds really good in my opinion, it is quiet at low rpms but really screams at WOT....... and it makes a few more hp too.