Again, if there was a shelf piston it would have too big of ring grooves, etc. And who has driven one enough to need .030" over? This isn't the old days. If you need an oversize piston (and I have before) you just figure out how much over you need, and call Ray Barton and he will tell Diamond to make what you need. I wouldn't be going .030" over when .005" over will probably clean it up.