The 575 does not have a boost gauge, but when you are pulling a surfer up you can audibly hear the whine of the blower as it gets up to surf speed then the blower whine is barely noticeable once it reaches 11.2-11.5. Not sure I can expect to really lower my RPMs since they are 3500-3600 at surf speed. I don't have any problem maintaining/holding surf speed with the Acme 2247 now, I was just thinking if I am going to buy another prop why not find out if there was something more efficient currently being offered.