My GMC dealer told me I could put the lift put on and they were cool with it, but wouldn't warranty the parts, obviously. He also said that the GM rep for my area was hard on people who installed lifts, level kits, and programmers. He would pull the warranty if he came into the shop and an "altered" truck was being worked on under warranty. It didn't matter what the problem being worked on was. Kinda, put the kibosh on my plans.