the ORP is fine in FSP, just not STF/ST
STF is a new class being proposed (i think it got the go ahead, not sure) it separates those pesky Si's you've been chasing. it's basically a class for FWD pigs.
i've heard the best street tire class for the SVT is STX, but i think that has changed with the addition of STF. IMHO street tire classes don't really benefit the SVT since the power is just about maxed out from the factory.