oh gawd !!!...that 150hp shot changes everything....
He will need to be given two sets ups..one for the all motor and one for the NOS..You can't have the best of both worlds.....
there is not enough information in My opinion to give a NOS gear set up.
lobe sep on cam, ring gap,tire roll out size, converter,NOS spread, Nos fuel pressure, external fuel supply system, or one big pump, method of timing retard,......just getting started !
this can turn down so many rabbit holes when you throw NOS in the Mix.
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Bjuice..
"I'M YOUR HUCKLEBERRY ! "