I have a G-38 that was on a Giant Super sportster that lost the muffler when I was flying due to vibration. After the muffler came off, with no back-pressure on the engine, I couldn't get it to idle down (I set all my planes up so I can use the throttle trim to kill the engine), even with the trim all the way down. So I circled around, and killed the engine with the remote switch. I have a simple set-up to do this, as I mounted a radio-shack switch (cheap) to the side of a servo, and one of the big round servo wheels on the servo (it looks like a cam of sorts), all set up on my gear switch so when I flip the switch, it rotates the "cam", flips the switch, and grounds out the magneto. Its a simple setup that works fine, and even though I use it as my main kill switch (in addition to my outboard mounted grounding kill switch, and my throttle setup), so I have 3 potential ways to kill the engine. I do that with all of my gassers now.

Dave