Doing just a catback or muffler won't get you V8 sound. I replaced the y-pipe and main cats when my pre-cat in the driverside of the y-pipe broke apart. I shopped around alot, Random Technology makes a stainless steel pre-cat delete y-pipe and a stainless steel high flow single cat for cheaper then it would cost to get the oem steel y-pipe and dual steel cats theat can rust out, break apart, etc...
I installed these with the Flowmaster 50 series and dual 2.5" tailpipes (homemade pieced together from older tialpipes), this setup sounded good (really droney though).
The Flowmaster rusted out along with the tailpipes within a year and a half. Last summer I replaced the muffler and tailpipes with a stainless steel MagnaFlow 2.5" in/ dual 2.5" out and aluminized steel 2.5" tailpipes (custom bendand welded by me and my buddy).
Let's just say I get asked all the time how I put a V8 in a 1st Gen Sport Trac. You can hear my truck from over a mile away and if I get on it, it sounds like an old Hemi.
I've tried to get sound clips and video clips but the camera and my iphone cut the sound off as soon as it gets too loud (which is as soon as I start up the truck).