That is rather dismissive and insulting Crump, particularly given that he is right and you are wrong.
If you were right the Spitfire Mk XII would be faster than the Spitfire Mk XIV because the Griffon IV has a lower full throttle height than the Griffon 65, yet we know that this is not remotely true.
The higher that a full throttle height is the faster that aircraft will be, all other things being equal, because the engine with a higher full throttle height is producing that power where the air is thinner and therefor the aircraft can reach higher true airspeeds.
As such the Merlin 266 with a full throttle height of 19,400ft would make for a faster Spitfire than a Merlin 66, with its full throttle height of 16,000ft, Spitfire. That is only in terms of absolute top speed at fastest altitude. At 16,000ft the Merlin 66 Spitfire would obviously be faster.