They are just trying to mess with you. I could go on into long story’s etc, but to keep it short and easy NO they can not void your warranty. Hell the damn Chevy dealerships sale lifted trucks off the lot I believe procomp is brand of lift or another well known company. You might have to fight it but I have had two cars/trucks with allot of work done to them performance as well and have gotten everything covered. Now one I did have to get lawyer due to it was a whole motor and even that was covered, and that was a motor with a aftermarket turbo kit installed ( CTSV ). Something my lawyer told me before, ( it is the dealerships burden to prove that the items changed caused the failures not yours ). If you don’t want to fight a lot or get lawyer, and IF they have not red tagged you then just take it to another dealership. PS my truck has intake, exhaust, tune,lift, 22x12 33’s, traction bars etc and the dealership replaced my lifters when they failed my A/C as well as my transmission when it smoked. YOUR DEALERSHIP IS A DI$k. Sent from my iPhone using Tapatalk