http://www.osengines.com Perfect for 3D, precision and sport flying, the 1.20 AX Engine delivers 20% more power than a .91, and will bolt right where the .91 used to be with CCD technology. The Power Box muffler includes straight and 90 degree adapters and eliminates the need for expensive aftermarket mufflers. No other engine manufacturer offers the Power Box muffler. It comes with two adapters – one for turning the muffler 90 degrees to become a “Pitts style”.