Dealers may not be your problem. Its the area warranty rep. thats a pr_ck up here. He is denying warranty for exhaust systems, air intakes, tire sizes (two bigger than stock), programmers, even gauges in the cab
. Its total BS, they put the burden of fighting them on you and how deep your pocket book is.
I only had small issues, but its the principle of it. I will not buy another new GM product until there is some big changes with GM and how they care for there customers. So I guess to answer your question, be careful with the Mods that hard to reverse unless you want to chance a fight with the warranty Douche Bags.... Rant Over