I was looking for a performance programmer for my 2001 Chevy Silverado and I came accross these guys:
www.wait4meperformance.com
For $158.10 they'll send you a PCM programmed the way you want with free lifetime upgrades or changes. You can return you're old PCM and get $60 back, I plan to keep my old one. I ordered one so I'll let ya'll now how it works.
I asked for something pretty aggresive with an even more aggresive map when you push the tow/haul button.