i know this may seem like im being too cautious but ive been having so much bad luck lately that i want to make sure i get everything right. i recently purchased a new head unit (after the theft of the 1st) and im going to have an installer put it in. this guy is new in town but a mutual friend recommended him to me. hes going to be installing a dd avh-p4200dvd into my 2000 gmc yukon which has the 1 1/2 din dash. since hes gonna have to customize the dash are there any things i should be make sure he does or doesnt do? just trying to be careful.