Something about increasing the capacity of the bottom end of the engine, aparently in this engine it allows you to run it richer without sacraficing fuel mileage or power.. thats what i've been told anyway.
If it really made a big difference im sure companies like Novarossi, Top and JP would be doing it.
The Hyper 21 pro w/ boost has a claimed 2.7hp, so its no slouch - dont know how much of that is the 'boost' chamber though..
Hows the TT coming along Tim?