[Goat Blower]

Yeah, all the FIAV does is allow more air around the throttle plate for a higher initial idle, which in turns warms up the car slightly faster. When the coolant warms up, it melts the wax pellet in the FIAV which blocks off that air passage and lowers the idle.

And cold pistons don't equal piston slap. Stock pistons are cast which expand very little compared to certain types of aftermarket pistons, so piston to wall clearance is tight so you're not getting piston slap. Plus pin offset and the skirts also guard against the piston rocking at all in the bore. You get initial piston slap with brands like J&E or all out race pistons because they're made from a tougher alloy, 2XXX something while most street/strip pistons like Wiseco's are made from a slightly softer alloy, 4XXX something which has less tensile strength but also doesn't expand and contract as much as the 2XXX something alloy, which requires a lot of wall clearance for expansion.