nana dohc is proven to better overall for power otherwise why would formula 1 and so forth use it. if the zr-1 engine would have been revamped for the zo6 it would have been better. it was making 385 and the origanl zo6 was making the same power, and a dohc eninge tuned to teh same compatabilty will be better then pushrode no quetions about it it is more expensive but it is better