Whats the best way to remove the stock muffler and install a new one?

I've read that its better to go with screws, cause welding the pipes is too much stress and it wont be air tight. But how do I hang it up to the body?
Can I just hang it on a metal strip, which i just screw into the cars underside, or?


I've got 2 aftermarket mufflers for $25, still cant decide which one I want to install. The oval one will look better IMO, but does any1 know which one makes deep "wroom" sound? I dont my Benz to sound like Formula 1.

(sorry for the mess in my trunk, i forgot the juice )