speed pro coats there skirts to run them tight or teflon buttons in racing to cut the drag this was a old trick we just run them loose there as been many advancement in the alum and the skirts so if you are asking if i would do it for a all out engine yes i would think about it .have used many of the coated pistons but have never look at them after i put them in and i never run them at the min piston to wall coated or not but with the coating you can run them abit tighter i put them in the mid point