EDIT you said HERS, nevermind.
I don't see why they would make the cooling holes smaller though, even if you had heat exchangers extracting useful work from heat you still have the same net hear output. (I suppose you could make the inlets smaller, but to conpensate you'd need a bigger outlet)
It's also not really relevent to the original problem of using limiting cooling capcity to limit power output. Adding heat exchanges and extracting work from the heat wouldn't do anything to limit engine power as you are adding a second cooling system.