Lee. I've had quite a few of the GP Spinners and I think they look pretty good. All of my spinner prop openings had to be filed to accomodate bigger props. After I filed the prop openings, I put the spinner on a wheeled prop balancer. Each and every time, the spinner was way out of balance. I used a drill press and removed the excess weight on the "heavy" side of the backplate. I didn't drill all the way through, but just dimpled it to remove some aluminum material until the spinner was balanced. Oh, just like everyone else, I removed that spinner retainer mechanism first. That seems to have worked pretty well. With a large single cylinder motor, the vibrations seem to be more apparent at idle and low throttle speeds. As the engine rpm's increase, the vibration seems to be greatly reduced. Don't let that fool you! The vibration is still there with an out of balance spinner/prop, it's just radiated through the aiplane at a differenty frequency. This can cause RF interference, early loss of battery capacity, premature servo failure as well as attack the integrity of the glued joints in your plane.