Shutting your engine down gives no advantage at all. Chopping your throttle to 0% is a much better way to slow down. On a 2 engine plane, its the same story. If you have 2 throttles, you can control each engine independently, and while being able to have the engines at different power settings would give you a slight advantage (if you knew what you were doing), totally turning off one of those engines would be stupid. My theory is when you turn off an engine, the game auto feathers your props for maximum glide, so you don't slow down. When you go to 0% throttle with the engine on, it doesn't do this, so there is a lot of drag and you slow down a bit better than if your engine was off. Now this is just my guess and you would have to talk to HiTech to know for sure. I could be totally wrong. All i know is I've fought pretty much every "great" pilot in the game, and I have never known any of them to shut their engine off in a dogfight. That alone might tell you something.
