[Bruce Edwards]

The coated ones run tighter and cause less wear on the bore. The flat tops will give you a bump with out head work. I do not like dished pistons in performace engines. It is my feeling that a flat top has a better flame travel than a dished piston. I smooth out the valve pockets with sandpaper to remove any sharp edges, clean the piston before you install it if you do this, to help cut down on hot spots caused by carbon build up. The carbon will form on any ruff surface it can get a grip on. If the carbon gets hot it will glow and cause the engine to ping or knock. Bad for the pistons, rings and bearings.