Borla... They had them on the clearance section of their website for quite a long time. That is also where I bought my GMPP Hummer H2 tips (directly from Borla).

Some time back I posted a link on here to the specific sets on the Borla clearance page. Looks like other than the tips they only have exhaust sets left for the H3's.

https://www.borla.com/products/closeout_corner.html

I have the GMPP cat back set (I did not get the exhaust directly from Borla but I did get the tips from them) on my 2003 and the paperwork it came with had Borla noted on it in a couple of spots but everything was labelled GMPP. Have that GMPP touring set paired up with some long tube headers and I'm pretty happy with the setup. I could stand for it to be a tiny bit louder but I did have a Flowmaster big block muffler on prior which sounded great but the drone was pretty bad. The GMPP borla stainless on now has no drone and does sound great. The official H2 embossed tips was just the icing on the cake.