exhaust throttles?

Hi , I had a few searches regarding exhaust throttles but cam up with zip.
Has anyone got any links, info or can they explain a bit more to me.
can they be used on gas engines??cheers JC

Exhaust throttles were the rage in nitro engines 20/25 years ago and when set up right were a really good system tho quite messy for most.

In our gas engines primary reasons we don't see them being used is HEAT which is a lot more than the nitro engines and lack of discharge oil to keep it all lubricated. Under the heat generated really no effective way to have a control valve that seals well enough and able to handle the extreme heat. Because of the flammability of gasoline a fuel belching leaky ass valve like we got away with years ago just won't cut it.

I messed with them a couple years ago...made my own with different shapes/sizes of gates...in the end I gave up...didn't see any advantages to it but did see very poor low-end to midrange. I think it could possibly be good for SAW. Don't think there is anything to gain for heat racing or just every day playing around.