DiMarzio Model P: big in the mids, grinds well, tastes great, less filling. http://www.dimarzio.com/pickups/bass...marzio-model-p
This guy did a comparison of a ton of precision pickups. The name of each file in this soundcloud is the brand of the pickup: http://www.soundclick.com/bands/defa...&content=music
I'd also recommend stainless steels for a precision, if you're looking for an aggressive tone. Rotosound 66, Dean Markley Blue Steels, and Dean Markley SR2000 are all good options for a gritty/aggressive sound on a P.
Lastly: overdrive/distortion can definitely help with the aggression. For overdrive, I'd recommend an Xotic Bass BB Preamp; for distortion, a Darkglass B3K.