There's a reason why people (like Sneap, Murphy, et cetera) use Tube Screamers before high-gain amps - the midrange response is crucial and people often neglect it. I'm going to agree with Stitch up there and say that you don't need a bassy pickup - your amp's bass response can be tweaked to fuck and back, and it's going to be much more helpful to look at something that doesn't have tons of low end.
Jeff
Jeff