Doesn't change the exhaust sound any. I just welded in short pipes in lieu of the Cats, and it sounded just fine. Got a crap load of power from that improvement, those cats are SERIOUSLY restrictive.
Once I upgraded the rest of the exhaust, top-end power just sky-rocketed. This was after a full engine rebuild, headwork, new intake, giant intercooler, removing the AC and some other happy goodies.
-S