If installed right IE the right gaskets and ARP studs. You will have no problems. O rings to me are a waste of time unless you are running serious boost (18-20psi) or tons of squeeze. I have always built motors with the fel pro 1011-1 or 1011-2 gasket and ARP studs and I have cracked pistons and blocks before the HG blew. Its all in the tune, the machine work and the install. Even though they tell you to install them dry, I always use Permatex Copper Spray on my gaskets, that stuff DOES make a difference and its works!! I detonated my 306 last year on 12psi so bad that it cracked my block in the #8 sleeve and took a chunk out of the piston, but the head gasket was fine.....