GMMG and Stainless Works offer chambered exhaust if I remember correctly. I'm not sure if Stainless Works does anymore, but I've seen some truck systems that were.
Personally, I've had a Borla adjustable catback (CB) on my '95 and '02. I love the exhaust because it fit great and was adjustable. In my '02, I also have an electric cutout where the difuser plates go and I can adjust it with just the flick of a switch right now. I can go from being heard a mile away to a very controlled, near-non-existant raspy/resonant tone.
I think I'll be looking into systems from GMPP, Magnaflow, and SLP this time around. No offense to any Corsa guys, but I've never really been partial to the sound on the cars and trucks I've heard (but those were mostly Camaros with LTs and that sound just didn't appeal to me; it was tinny without being raspy - hey, to each his own
). I think the GMPP CB will be made my Borla or Corsa so know the fit will be great and they'll be stainless and perform. I know the SLP, when it comes out, will be no different and I think the Magnaflow will be just as good and maybe the least expensive. Who knows though? With all the CB out there getting past a thousand bucks it'll be a tough choice and come down to which sounds good and makes the best power. If GMPP comes through with an off-road system, I'm likely to go with that and get GM's warranty, and if not, I'll be looking toward the companies that do make a bullet-style system, because mufflers suck (or blow, or whatever). I'll probably put some electric cutouts just past the cats' too, just for when I need to be heard