they handle 9-10 SAFELY if you use alchol injection.
After finishing my suspension and race brakes (doing full course racing in the spring), I plan on upgrading to the DH Racing shortblock, and a ported head. Should be good for about 400whp at about 20-22psi.
And yes I will have an aftermarket clutch by then, it's my next mod, along with LSD

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*EDIT - That 400hp is just a guess. Until I port the turbo and upgrade to a 3" turbo back exhaust, it looks as though 400 crank horse is more apporopiate.