Adding 22 cubes,,, power increase? 528 to 550

You can use it for that, but you can also use it on a fresh engine. That's what I'm going to do.

What ends up happening is you end up with near zero running clearance, which makes the piston more stable in the bore, which increases ring seal.
How much clearance are we talking here. The trend with Pistons nowadays already is tighter than say 20 years ago. I bought new custom Ross Pistons uncoated and they recommend .004 clearance.
Can you put a number on it?