The only time I have seen an inducer slow a boat down was when it was added to a boat with a high rpm engine that couldn't pull the impeller cut that was in the pump. A "V" blocker grate was used to starve the impeller of water so that the engine could turn the impeller to the rpm it needed to be at "on the cam". This is what blocker grates do. We are NOT discussing tail "lift" here, tail lift only changes RPM if it changes impeller load. If the blocker grate is removed and replaced with a normal loader grate and the RPM goes down, impeller starving is what was happening, whether you believe it or not. This setup is common in drag boats and not seen TOO often in lake boats. When a blocker is run in a lake boat at high speeds for very long, impeller "burn" (cavitation) is commonly seen, as are cracks in the impeller. The next thing usually done is to add a stainless impeller "because I have so much Horsepower that the aluminum impeller can't handle it". We can allways tell who uses blockers, because they are the guys that brag about how much Horsepower they have, based on the engine RPM/Horsepower impeller chart. Those charts are essentially worthless. They are entirely dependent on impeller loading. Change the grate and change the load and it changes the RPM,change the nozzle size, same thing, but did the Horsepower change? So much for the chart..... An aluminum impeller that is PROPERLY loaded will absorb 1000 HP for a long time.
Also, some auto transmission high stall torque convertors restrict the fluid flow within the convertor to alter the stall speed, and "hit" characteristics too. Same principal. For further info, ask the pump MANUFACTURERS, (Dave and Ron). You will get less B.S. that way. Let the s--t storm begin! TIMINATOR :argue: