and he still has the stock motor that came with the car in 1991. It was freshened up after an uncalculated risk was taken and the stock head gasket needed to be replaced. But all the original factory parts are still in the motor. And there aren't too many people here that put their motor through what he does.
We have yet to see what the stock internals can take. So no matter what kind of math anyone does, until a well maintained and tuned motor breaks simply because it's making too much power for the stock parts to take, no one can really say anything about what the stock parts can handle.
Forged is better then cast though. I am by no means trying to say anything otherwise.
