Heavy gauge strings = les string tension = low end tones
Also... finger picking will give you a lower end tone as well.. because the surface of your fingers are much softer than that of a pick... your flesh will actually slightly take vibration out of the string because its not a clean pluck. Picks will give more biting tone...
As for pickups... I don't want to go all the way to your post in the tone section... so I'll post it here... If you want sheer biting tone... I suggest the Dimbucker by Seymour Duncan... or a pickup with a ceramic magnet. Ceramic magnets usually have higher output than any other passive pickups and give the most high end tone... I would suggest equipping a Dimebucker in the bridge Humbucker position and a pickup with a softer tone in the middle... then for the neck go with the highest output single coil you can get... that way you can always select the brigde and middle... and neck and middle if you want to keep your high end and push in some lows as well... Good luck.