Christmas present or not, I'll knock it.. Boost bottles are nothing more than a very clever way of separating people from their money. On smaller engines, like say a .12 or a .15, yeah, they can add some punch. But on bigger engines, anything .21 and up, IMHO they throw off the balance of the carb and make them too difficult to tune. A kid at my track has 3!!!!! on his Hyper .21.. He consistently loses to stock Hot Bodies engines =)