Xtreme 4 banger, what exhaust setup?...

I have a friend with an Xtreme that has a 4 banger. What is a good setup for a new exhaust? I know when i had my 94 S-10SS i had a flowmaster with dual outlets (2") that sounded pretty good BUT didnt know the correct setup for a 4 cyclinder. Im just talking about a cat-back and not the whole exhaust. Has anyone used the Dynomax super turbo muffs curious on how they sounded. thanks