I've started having problems with the os plugs. Kind of sounded like I was getting some sort of detonation while in the midrange area. Top end seemed to be alright. Had to change the first plug after 12 flights. Developed a problem keeping it running. Now the 2nd plug isn't working well after 3 flights. Same problem keeping it running. That's enough experimentation for me. Going back to the ignition, this is getting to aggravating.