The engine really spools up smoothly with the 17 x 6 prop. I don't see any negatives to this prop, but I am no expert for sure. I am having trim issues when the fuel gets low. I have never noticed trim changes on other airplanes as fuel is consumed. I sure do on this one. After I re-trim and land for refueling, I need most of the up elevator to break ground and a half stick of up for level flight. I am seriously thinking of moving the tank back and using a Perry pump. I have no radios in the area forward of that bulkhead that is just aft of the CG. My throttle servo is just aft of that. I could center the tank over the CG, but it would be much easier and less invasive to locate the back of the tank over the CG. I guess this would be an improvement over having it against the firewall. I was just trying to avoid a pump on my OS 120AX. What are other's thoughts?