When I originally had the machine work done on my block he checked the deck and said I was fine and he didn't need to deck it. That was when I was going to run normal head gaskets and I didn't have a supercharger though. Like everything else on my car I have gone through 2-3 redo's before I got to what I really wanted. I got the MLS because I heard wonderful things about them for boosted applications. I just didn't learn how tempermental they are until I had them installed. I have learned that my block deck is straight, just not MLS straight. Live and learn.