I have a ST 3000 converted to gas using CH Ignition and syncrospark and their carb adaptor with a Walbro carb. It was mounted on a 19# bi-plane. It would fly it scale like, but it was no power house. It was mounted inverted, and tended to be hard to start the first time after sitting because the oil will foul the small 1/4" spark plug. If I use it on anything again, I will tap out the spark plug hole to 10mm.The larger plugs are cheaper and won't foul as readily as the small plugs. The engine ran good with a good idle and transition. On gasoline the burn rate was about 1 oz per minute at 2/3 throttle. However, the 19# bipe was just too much airplane for it. I wouldn't consider putting it on a 22# Mustang, but it probably would fly the Balsa Nova with reasonable authority.I have been contemplating building a 4*120 to put it on, but haven't got there yet. The ST will develop about 10% more power on glow fuel, but is a guzzler. In addition the ST carburator isn't very good. Most of the people who I know have switched the ST carb for an OS.

The CH ignition CD unit with syncrospark is about $140.00 and the carb adaptor with a Walbro carb is about $60.00 and a 1/4"-32 spark plug is about $15.00.

There are several mufflers that will work on the ST 3000 so that shouldn't be a problem.