I had my gsr block bored .20 over 5000 miles ago when it was rebuilt, blew headgasket with nitrous and now going turbo. Someone told me "whenever you change your pistons, you should bore the block" Is this true? im just going from 10.6 to 9.0 CR.

Also, does the ARP headbolts stretch? should i change them?

Thanks for looking

 

Not neccesarily u could get away with a bottle brush to clean up the cylinders so the rings bite and drop new pistons in, it would seal up cause bottle brush your not taking material out your just giving the cylinders a quick re-finish, then just get .20 9:1 pistons....Arp head studs can be re-used over