Thanks for the reply. I kind of thought thats where I should run it according to the performance, I just have heard from so many people that you don't want to run it too lean or you will spin the prop loose. I was continually trying to richen it according to doing a pinch test and I think it may have been rich enough to make it back fire, loosening the prop. This is my first 4-stroker and was wondering if the pump model would change anything while doing the pinch test. Thanks for the input.