If you do the mufflex, it "clamps" in. Cherry Bomb makes a similar kit, just different sound. OR you can have a shop cut out your stock muffler and weld in a new magnaflow muffler of your choice. Mufflex and Cherry bomb kit you could do yourself.
Here is my shop done Magnaflow http://ramforumz.com/showthread.php?t=71908
Wow, thanks for the info Timmy, rep for ya. I placed an offer on a magnaflow catback system on ebay. If he doesn't accept my offer i'll just pick up the mufflex!! Waaaay cheaper, and stock pipes are find