Sound like you got a special transmission there in the ZF.I wonder why the T-56 would not be enough especially when the Viper has 500 horsepower and i bet I am at 425-450 max.Do you powershift your car.I have a 225 Horse power Mustang Gt 225 Horse and i tried about 10 times to powershift on it and it finally broke 2 tranny's in 1 week.I have never learned how to speed shift either.Speed shifting puts much less stress then powershifting.Just wondering how you shift in your car??Doug Nash and Richmond's sound interesting also but I won't be able to find a ZF and when it breaks no one can fix it here in the states.