Make sure you have a good quality comp guage as when I tested comp with my elcheapo guage (was brand new) my 318 only registered 110 psi and my 410 said 140. seeing that my 318 was supposed the have 10.1 KB pistons with 61cc alloy heads and my 410 registered 140 psi and it was supposed to be 11.0 to 1 I was a little bit worried until I borrowed a mated Snap On tester. On the snap on tester my 318 showed 160 psi and my 410 showed 205 psi. So it just goes to show you their is crap tools and good quality tools out there!