You can use it on both on and offroad. You could custom make your own or I've seen ready to use ones from Dubro and HPI. I'm sure there are others.

Ok, I think I see what you're after. The high whine of a real turbo? Highly doubt you will achieve that with a 2-stroke nitro motor. The nitro sounds are naturally too high pitched and tough to change. Pipes themselves will alter sounds but still not to what you're looking for as they're designed for performance.