the hoses, and valve cover gaskets. It took me a while to get the plenum off. I think probably longer than some other members. Not sure of the total time but I think it took me about 1.5 - 2.5 hrs. I had to cut the PCV hoses cause they wouldn't budge and they were harder than rock. Just make sure that you remove all the hoses in the back of the plenum, or it will never come off.