CAT C15 blown headgasket on fresh inframe.

[Hermjeji]

Perhaps a more general question, not trying to hijack this thread. Parts being a pain, I have an mxs 475hp that runs the higher compression pistons. The only kit available at the moment from {an aftermarket company} is the 625hp version, which has lower compression pistons.

If nothing is changed ecm wise, keep the twins, etc., what's the outcome I get running the lower comp pistons?