it WILL blow up.

you cannot run CTR pistons in an LS block with a GSR head. the combustion chamber of a GSR head is too small, the piston dome on the CTR piston will hit the head. eventually itll pound the rod bearings out and rip the wrist pin out of the piston.

get a b16 head, r get rid of those pistons. compression will be very high, look at the 1st page of this thread. its around 13:1

P72 head/B18A/B Block

STD = 13.170743903246784
.25 OS = 13.236528215133324