Booker,

If you get in contact with Slimline, they can build you a Pitts Smoke muffler for your OS 300 Super Gemini twin. I installed a Slimline Pitts muffler in the Pitts that I built for another pilot that had the 300 in it. The tubes came out at the scale location and the sound is awsome! It had an onboard glow and battery backup sustem in it also. He did not opt for the smoke, tho...