OS Wankel..first version

These engines are not as noisy as most of similar size. Try making an exhaust extension from copper plumbing fittings and tubing; you'll find that to be satisfactory (and cheap).

I remember when my step-father got one in the early 70's, it didn't come with a muffler. It was quieter without one than anything we were flying with a muffler!

PCPhill

Hate to spoil your fun, but you may not think it has much noise. That's only what you hear! Unfortunately they have a high level of high frequency noise that is above most of our hearing range. If you allow yourself to be exposed to this for any length of time (like 30 minutes or more) you will have a splitting headache later that day. Furthermore it will contribute to hearing loss later on. I had to learn this the hard way, just thought I'd alert all here.

Olin McDaniel

I'll take your word for it. It was 30 years ago, and I don't remember any headaches ;)

PCPhill

I don't eithor, but I do have a hearing aid...