RE: 55 AX equal to Saito 72
Also try it with a 13x4 Xoar prop and a Tower Hobbies muffler. The Xoar lets it spool up faster and the pipe adds about 300 rpms. My 55 AX on a 4.5 lb PRIMO is an even match in a vertical drag race with my 4.5 lb MOJO with a Saito 82 and an APC 14x4W. I prefer the Saito for 3D because of the quicker and more even throttle response, but the 55 AX is at least a match for power.
Tim