I have a lot of respect for this part of the engine build and for those who know their stuff, so for those contemplating hot rod pistons, here is some advice from someone who has done quite a few: (from Endyn)

plug and play it's not:
"The boring and honing process is one that should be accomplished by someone who does little other than cylinder wall preparation. Good boring and honing is an art form / science, and while good equipment is essential, a machinist who has a lifetime of experience (and who charges by the hour rather than having a set price for the operation) is the only way to go, as the right clearances and a good ring seal are all-important to making power. If the rings don’t seal, all the other modifications in the world won’t do you any good, as the power will go right past them.

We bore and hone the block to the same specs we provide our piston customers. All boring and honing operations are referenced from the main bearing bores of the block, so the cylinders will be absolutely perpendicular to the crankshaft. We don’t ever use the engine’s deck surface as a reference point.

The honing process must be performed using Sunnen equipment, such as a CK-10 (or newer) automatic honing machine. BTW, the “automatic” part is a joke, as it still takes a machinist with lots of experience to do it “right”. Right in this case would normally be a clearance of exactly .0028” (to the tenth), with no more than .0001” taper, or out-of-roundness. Our honing expert (who does cylinder wall preparation of winning domestic Pro Stock engines) is also giving the cylinder walls “teeth”, for an even greater effective ring seal. These “teeth” cause the bores to be smooth when you run a finger down the bore, but extremely “rough” when you pull the finger “up” the bore. This texturing is just one of the many “tricks” necessary when competing in a class where all 16 qualifiers are within .02 second on elapsed time! Lose effective ring seal on one of these 500 cubic inch normally aspirated gas-burning engines and you’ll lose a hundred horsepower!

It takes 3 hours of “finesse” time to hone our awful cylinders and before we’re able to get the bores straight and true, we’re looking at .0039” piston to wall clearance….which is “real loose”. We will shrink that clearance to the more desired dimension, however, with some very creative work on the pistons, as you’ll see later on."

 

Well that is the answer I wanted in the other thread.
So much dancing around it is hard to find the right (partner) answer.
Thanks for the facts. The truth is always better than all the fiction, I have been reading.
Buy this, Buy that. Buying is not the answer, the truth is, and you have provided it.

 

to elaborate even more:

a properly designed piston top and combustion chamber shape is intended to improve combustion efficiency. that means you should need less fuel to achieve the same A/F ratio and less timing advance.

A real tune using new pistons would have to address these parameters or you might end up running richer than before and with the piston pressure developing a max too early and before the psiton is on the downstroke.

 

Don't forget a torque plate.