I have the same question on as to no avail. I installed .25mm over mahle powepaks in my Aug 06a block. I know squirter clearance is an issue with aftermarket pistons. I'm wondering just how much I need. The machine shop I had it bored out at recommended .040 inches. I was able to fit a very thin piece of copper between the inside of the piston skirt and the squirter with some play. I could also fit it between the bottom of the piston and the top of the squirter. Is this enough clearance? The guys at the diesel shop say it is. And I only checked number four as this seems to be the most problematic. Fyi the id estimate the copper to be around .25 to .5mm.