I just looked up didn't find any dyno evidence, but one thing I seen Nascar put a limit how small they can go with main of 2" or other wise the teams would just keep going smaller, so obviously there's room for gains at that level but like you said doubt an average guy builds gonna matter. One other interesting thing the guy said if your bearing look good when it's rebuild time your leaving power on the table :) obviously meant for engines gone through all the time.