stock exhaust sounds great IMO, its the downpipe that you have to modify, once the restriction is gone there, it opens up the sound of the stock exhaust to something a bit more V8 like. This is my car with stock exhaust and a 3" catted downpipe and OBX headers.

https://www.youtube.com/watch?v=SQRdQr7tDKA

I grant you that its cammed but if your looking for the V8 sound, you have to get rid of that goofy V6 downpipe and 800 cell cat.