I did a similar swap on my truck a few months ago. I bought a Holley Flowtech muffler, a 2 ft 2.25" extension pipe, 2 hangers and some clamps - about $50 total. I had to get the pipe and one end of the muffler expanded at a local shop (+$10) to get it to fit the oddball size stock pipe. I probably should have got the aluminized version, but it wasn't in stock at the local Checker Auto. I turned the outside edge of the muffler up about 30 degrees to get the outlet to line up with the tailpipe, but it still has more clearance than stock. Mine isn't as loud as I thought it would be either, but does have a nice rumble. I did the same swap on my wife's '00 Dodge Durange, that 5.9 sounds sweeeet now...
- JohnF