Just curious:
Where the 72" Manifold pressure number came from. I fly real world Mustangs and we would never use more than 61" on a stocker. The manual in a "D" or "K" would allow 61" or up to 67" if in an emergency. But that time above 61" was supposed to be logged and maintenance possibly would be performed(the real crews may have pulled the plugs or oil screens or some other things but I actually don't remember what I was taught about the post flight High power WW2 maint sched.) I do know that with 115-145 octane which was considered "HIgh Test" fuel, that you are limited in MP even if you could get more than 67" out of the blower, on a hot day, you could detonate the combustible air charge prior to proper time so Detonation or pre-ignition could occur and parts get destroyed in the engine. At Reno, when we run high power, we put a 50/50 mix of water and Methanol injected into the air intake after the blower and prior to the intake valves to cool the compressed air charge that got heated up by the blower. Many more variables there but the concern is potentially a too hot air charge going into the cylinders. I have forgotten which late model 51's had water injection(ADI or Anti Detonation Injection)Maybe anything with a dash 7 or dash 9 ran ADI and 80" but still 3000RPM.We run up to 150" and 35-3600 RPM when pylon racing. This allows the carb to be deriched which means it brings the very rich fuel/air mixture into "Best Power" and more horsepower is gained from the combustion. (Like a few hundred when dealing with the 1490 HP of an early dash number Merlin). The RPM is governed by the prop governor so the RPM Remains Constant and so does the MP when ADI is turned on. You would just see an increase in performance and "IF" you had a fuel flow guage, youd see a 16-18% decrease in fuel flow.
Basically, I'm just pointing out that the 72" number is a "Could be" but I have not seen too many boost controllers set to go that high.