ORIGINAL: MinnFlyer
ORIGINAL: js3
Some people mistakenly state that they are quieter.
No mistake about it. The latest version of the 91 surpass REQUIRES muffler pressure. But before that, I usually ran my 91's without any muffler at all - just a straight pipe. And I still run two of my OS 70's that way
Oh, and BTW, nobody complains that they are too noisey
Ok, I'll concede the point if you're talking about muffled four cycle motors. That's just it though, most people don't muffle their four bangers. The most popular four cycle motors where I fly are YS 1.20s 1.40s etc. They are every bit as loud if not more so than the loudest (muffled) two cycle and to my ear, the sound is much more obnoxious with the YS than my Jett racing motors.