Hello; My first engine was a Webra 40, which made lots of power but never ran right, it was too loud so I bought an OS 40FP with a mute kit in the muffler which worked much better. I used that engine for 4 years with no problems at all. Then I discovered 4 strokes and got an original Saito 45, which I put on Plane after plane after plane, I used that engine exclusively for 8 or 9 years, then I got a little richer and started to collect 4 strokes, I have quite a few now (more then 30) and don't use 2 strokes at all any more