2 of my buddies have 6.0 trucks and they had their coolers welded shut. they also installed head studs and new head gaskets at the same time. anyways, they run the shit out of their trucks, drag race, tug a truck, tractor pulling. no problems. after seeing it done on 2 trucks, i recommend getting it welded shut. dont waste your money on the delete kits. niether truck has a check engine light on either. the pcm doesnt know the cooler is blocked off. as far as warranty, just check with the dealer before you go in for warranty work. some dealers are cool with it, others are not.