The situation is probably more complex that Greg implies. Most of the noise comes from the input load resistor – if this is lower, the noise level drops, but so will the tone. This means that a booster which will improve the level without changing the tone will be hard to find.
Depending on your guitar and your ears, you may be able to find a solution, but this is not guaranteed – a low level output from a guitar is hard to use with digital inputs.
