I can put a clip on from my truck. It's a stock 5.3 with a magnaflow catback. Pretty weak really, but I haven't istalled longtubes or an ory yet.
mike has some decent ones of his truck (6.0 with a lil baby cam and headers)
it sounds pretty good. I just put magnaflow on my blazer, really woke it up. I would say gibson/magnaflow are your best bets.
blown transmissions are about as useful as 97% of the guys on this forum