Piston slap

NO there's no magic stuff to add metal to pistons to tighten them up. Other than the noise it causes there is really no harm for the pistons to fit slightly loose and make a noise as long as oil consumption isn't excessive. I bet it's louder on a cold startup up and reduces when hot, this is because pistons expand when everything gets hot. I have a 88 S10 Blazer that been that way since new and never had problems and never wanted the dealer to do the repair since it might effect oil usage. Mine is slight as it only does it for about 30 seconds when cold.

Could you explain what that's going to do. Higher octane only helps engine ping & detonation.

My bad...that's how I'd interpreted his description.