I had a 24" bbl. sx2 that shot over 200 with hevi 3.5" 5s with a .675 IC or a Kicks .680. I also shot nitros in this gun, The IC.675 and Kicks.680 both outshot the rhino .670 with any load.
IMO .675-.680 is the sweet spot in the Invector + guns.
A buddy had a 24" bbl bps that gave the same results.