A BLOCK GUARD GOES BETWEEN THE BLOCK AND THE CYLINDERS. THE B BLOCK IS OPEN DECK AND THE CYLINDER MOVE UNDER PRESSURE WHICH CAUSES HEAD GASKETS TO BLOW IVE HEARD.

IVE SEEN 20+ PSI ON A STOCK SLEEVED B18 BUT IT DIDNT LAST TOO LONG. IVE HIT 20 PSI ON MY B16 WITH JUST A BLOCK GUARD WITH NO PROBS BUT I TUNED THE AIR FUEL UP TO 24 JUST INCASE I EVER GOT A SPIKE.

ID SAY U COULD SAFEL RUN LIKE 15 PSI WITH NO PROB IF PROPERLY TUNED. AND IT SHOUDL LAST IF U GOT THE RIGHT INTERNALS.