[ProDigit]

In the case of the rebel, I will not see any increase in efficiency.
In fact, a turbo on an engine ALWAYS reduces mpg, not increases it.
A 1.4L NA uses less fuel than a 1.4L turbo.
It ready depends, but an eco turbo engine uses up to 20% more fuel.

They're looking at, if you'd compare engines HP wise.
A 1.4 L Turbo has about the same HP as a 1.8L NA, but with the same gearing uses around 5-10% less fuel.

It's all based on the fact that most cars spend their time idling, or cruising. In a scenario of start stop traffic, the turbo will have worse mpg than the NA.
Idling or cruising at a speed under where the turbo starts boosting, the turbo engine uses less fuel, because it has lower cc.

At HP peak rpm range under load, usually the turbo uses a lot more fuel.

Turbo engines are only efficient if they are used to boost engines when they accelerate, but are idle when cruising.

A too small turbo, will rob the engine of power (HP) and focus power at lower RPM (torque), and is best paired with taller gears.

A large turbo, only kicks in at the higher rpm, under load, and is able to increase HP, at the cost of a mild reduction in torque at mid RPM.

Adding a turbo to an engine, Always will reduce MPG, but it can make sense in the case of a rebel, that only makes 25HP, and top speed of 75-80MPH, if more top speed is needed.
If well tuned, the turbo can double Hp, however, if HP would just increase from 25 to 35HP, the bike's top speed would increase from 75/83 MPH to 85/93MPH, which would be enough for the interstate.

Considering the Rebel's weak clutch, it won't be able to handle a GT12's added power. And a GT06 would only increase acceleration, not top speed.

Then there is a problem with the fuel vapors injected before the turbo.
They might actually dissolve the oil in the turbo housing, and I fear it igniting when the turbo gets really hot (a possible issue on the GT06 at full boost, due to it's small size and low heat dissipation. Not an issue when just compressing air though..).

injecting extra fuel in the air duct after the turbo, might be harder to do. Some people have just used an electric fuel pump, to pump in fuel under pressure in the carburetor...
The problem there, is that the bike runs rich (air gets robbed by the turbo, and too much fuel gets added by the pump), and at load, the turbo still runs so lean that the engine starts stalling.

The proper way is to get a fuel management system installed, and that is expensive.
I was hoping for a cheaper solution :/

Still more to read up on, but with prices of the GT06 so high, I don't think this will work out (the gt12 would only offer boost at around 5000+ RPM, but I'd have to restrictions it's boost, not to blow up the engine, basically making the GT12 not an option; while the GT06 gives extra torque, while not giving extra top speed, not what I'm looking for...)

If they had an other brand turbo that was in between a GT06 and a GT12, that could offer a solution?
Still, no workaround the fuel injection system.