Maybe that was his intent, but I still think they put a Merlin 70 in there. 18 lbs of boost and all, not 16.
Thats beside the great "acceleration debate" which I think is not settled by the IX having either engine. Im not going there

But I am interested in the flight model of the AH Spit IX, and what it most closely represents.
Me, I think its a H.F. IX with a Merlin 70, slower at low alt, but faster as it goes higher, with 18lbs boost max.
I have taken one up to 43, 500 ft as well. Its not ez, but it can be done.