Just from a quick search, On roughly a 250whp n/a motor people were seeing 4-5whp across the board from an electric water pump setup, take that into account with the 16v battery and removal of the alternator which realisticly should take more power to turn than a water pump you could be looking at an easy 12-15whp gain by doing both together. Just a thought for you all motor guys.
My main concern about doing the whole thing isnt the 7-10whp gain from removing the alt but to keep voltage above 15 volts all the time to properly power the electronics and biggest thing the fuel pump. Fuel pumps dont like to see much less than 13 volts especially when seeing high pressures up to 80-90psi.
Also like it because it really does make more room in our small engine bays and cleans it up nicely.