I still think there is some merit to manifold pressure triggered systems. Detonation is very closely tied to cylinder pressure but not closely tied to engine rpm.
For example in the high rpm example given you would not need 2x the water for two reasons in my estimation. One since at high rpm your cylinder burn time is only 1/2 as long, engines are much more prone to detonation at moderate rpm and high load than they are at high rpm. In fact Honda found in their F1 engines that if you twist the engine fast enough detonation almost goes away as an issue since the shorter combustion time does not allow the high temperature decomposition of the fuel air mix to take place.
Also as most engines lose volumentric effeciencey at higher rpm, for a given manifold pressure cylinder pressures will be lower at high rpm than they will in the same engine at an RPM near max torque where VE is best.
You need the most water near max torque rpm at high load than you do at higher rpm.
A combination of the two systems is probably the best to get the most detonation protection for the least use of water.
Larry
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