Bore is 4.375. I will be using a plate Nitrous kit at 200 to 300 shot also. On my current 496 I had to machine tops of the piston .010 and ran 250 Nitrous shot, I used 1009 on my current 383/496 without any issues. Going with the 400/512 would the Felpro 1105 hold up to Nitrous as well as the Felpro 1009 did? I'll check to see if the Felpro 1009 hangs in the Bore . How would the thicker 1105 affect Quench? Thanks for everyone's help on this, Matt