This is probably what you will end up going with. (Cometics) I ordered these for my Keith Black 572 and ended up going with .060 thick to give me a little cushion with my B1 heads and nitrous. Saving these for if I build a NA combo. They measure 4.515. If you are going to order some get your order in. My last three sets took 6 months, 2weeks, and 6 weeks for my last set.