I had a Dimarzio Willpower P. If you want to stick out more in the mix then this will definately help out. Very midrangy and it really grunts and grinds. Can be pretty harsh sounding though, a little too much for my taste. To me it also has a more "modern" sound than Fender's P pickups, wasn't really what I wanted.
So I switched to the 62 Fender P pickup after I saw these videos.
Bass starts at 1:38
And he is using light gauge Rotosound Flatwounds, I wish I could get that awesome sound and punch out of them like he can.