I was reading on wikipedia and I came across this excert. I wonder how much more efficiency would be gained?

http://en.wikipedia.org/wiki/Superch..._turbochargers

That is doing this right?
Turbo -> S/C -> Engine

vs twincharging which is
S/C -> engine -> turbo

 

Almost all vehicles that are "twin charged" are Turbo > S/C > Engine. It's the "easiest" and most compact way to set them up. The other optiion is usually putting them in parallel, but requires much more control than most people are willing to deal with. I've never seen a S/C > Turbo > Engine setup, and am not sure why someone would go that route, it would almost always take up more space (volume) than the first option. Technically, any turbo is going to be both before and after the engine depending on what side of it (intake/exhaust) you are talking. Not really sure what you mean by "S/C > Engine > Turbo."