Nitro is right.. but just to elaborate..

Since your RC engine is going totally berserk, pulsing along at 300-450 reciprocations per SECOND, you probably guessed that theres some serious thermodynamic stuff going on in there.

The boost bottle is pretty much an empty bottle that hooks up to the crankcase of the engine. When your piston closes the pots, the "backwash" of air/fuel enters the boost bottle and in the perfect world, you'd want to tune the bottle to resonate with the engine under peak power.

A boost bottle wont exactly increase your HP but it may lead to a more reliable torque curve, and smoother throttling.

But unfortunately it takes some drilling (of the crankcase) to install this. and since your drilling, you need to take the engine apart to make sure you dont have any filings on the inside. On top of everything, this is also another place for air leaks!!

So, unless it comes factory like that OS engine, its prolly not worth it

ram