Dino,


With a gas engine, you will get more power with an open exhaust, than with a Pitts muffler, or another restrictive exhaust.
This is also true of glow engines, but then you will have a very bad idle quality and transition.

When compared with a tuned muffler/pipe, or a canister muffler (45 and 58 cc), the quieter mufflers make more power than an open exhaust. So why suffer with all that noise.