A Power boost valve is usually the way to go if your car is running lean. A lot of manufacturers claim 1.7 times faster acceleration as the fuel is (variably) pushed faster into the engine.
The idea is that your standard valve will send fuel into the engine at a standard rate, regardless of whether if you are booting the car (high revs) or not.
But the PBV will send the fuel at a variable rate.I.e. the more you boot it, the more fuel is delivered more quickly into your engine = faster acceleration.
But sometimes these things lead to engines running too rich, so be careful in regards to installation/tunning etc.