Isn't this statement a bit contradictory? If the pistons start out looser and expand faster a tight piston to wall clearance like .002" will leave not much clearance.
What I'm talking about is machine shop engine honing clearances. I will need to find the paperwork on the piston to wall clearances where it shows NA engines all the way up to Blown / Supercharged and as you go more radical the P to W clearances increase. More power, more heat, faster expansion rates = more clearance. I found the ring gap paperwork from Wiseco but the piston paperwork is MIA somewhere.
All I'm going to say from experience is that if you put a brand new set of pistons in your engine with a stock P to W clearance of .0015" - .002" and you run the engine any other way than normal driving they will be scuffing the skirts and the cylinder walls after a few good hard runs.