Fine-tuning the gap will help performance but you have to have the patience to do it. Gotta sneak up on the target gaps because you can't go back if you file too much. Go by the piston mfg. instructions because gap specs vary. Hypereutectic pistons, for example, require wider gaps. Basically file fitting rings is to minimize blowby but there are different recommendations and differences between top & second. Top & 2nd ring tension can be adjusted by back-cutting & spacers, usually done on class cars to get the most HP out of a combo despite the high cost. Oil ring tension adjustment is more common and cheaper. That's determined by the expander under the oil rings.