ok was wondering if it'll be alright to run pr3 piston in my b18b motor, i want to know the clay distance between the pr3 pistons and the stock ls valves....will this setup be ok if im planing to get an after market head gasket? what about stock head gasket? does any have the specs on stock ls valves?? sorry for all the questions.....

 

I think you would have enough clearance for those pistons as long as you stayed w/an oem 3-layer headgasket or larger. It will definetly bump up your compression but while your at it you should have it all done at the same time. Anything you plan on upgrading should be finished while the pistons are being installed. It will be much cheaper to tear the engine apart once than multiple times.