Roger that, I will give it a try. The article in RCJI I was refering to earlier mentioned the cause as redetonation of the unburned fuel being pushed back into the head due to a short critical lenth of the tuned pipe. They claimed that the shockwave came back too quick and pushed unburned fuel into the motor at the wrong time. I can't see why that would cause a sandblast effect, I can see how that could cause a hole in the piston though. Anyway, I will give her a go. Thanks again for the info., always better to have two heads on a problem. Mike L.