Could have been the Pistons, OR, the stock, non polished, BROACHED, LO PO Rods(I can tell at a glance). If it was the Piston, The Rod wasn't far behind. They aren't really designed for the use a Jet boat will put them thru in this form(loading and unloading at 6500+ rpm is really stressful). Al least, switch to a Rod that is Polished and Shotpeened(properly), and has SPOT FACING for the Bolt seat. PLEASE use an ARP bolt(doesn't have to be the 'Wave Loc' type, just 8740 is a real upgrade) and kmake sure the Rods are prepped. They'll last like that a good, long while under hard use. JMO. RR