Currently using a 2.38 upper with stock lower.. Getting 15.5-16psi. About to go with a cam so Im going to replace the dampener with ATI. Saw lots of threads on this, but nothing concrete. Im just wanting the same boost as I am seeing now. Was thinking 2.38/9.1? I do have a 2.55 upper that can be used if it makes it easier to achieve what I'm looking for. Maybe 2.55/9.55? Car is a FBO car.. Stock blower & snout. Thanks for the help!