How do you overdrive pickups themselves? Surely that is impossible.
Jack Casady used to add a second magnet to the Bisonics back in the day. Some came from Hagstrom with two magnets on the back, and some came with only one. Jack had an extra magnet added to one half of his signature Epiphone's pickup as well. Jack definitely seems to think that magnet strength alone is enough to change a pickup favourably.
For reference my repro Guild BS-1 (I wonder who made these? Artec? G&B? There is a Far-East OEM feel to this pickup), has two magnets, and is a 'bridge' pickup.
And that quick connect thing can get in the bin.
I thought the Bisonics in Jack and Phil's basses were stock, and it was all the downwind primitive active stuff that was the unique bit. Phil, Jack and the proto-Alembic crew favoured the Bisonic because it had quite a flat, even response and wide bandwidth. It made a good pickup platform to start shaping tone with active systems, because it provided such a 'blank canvas', tonally. That is why I can't quite drink the Dark Star/Bisonic KoolAid. The Crown of Creation/Live Dead tone is the product of uniquely modified basses with other stuff going on in them, rather than the tone of hotrodded Bisonics. Live Dead was an EB-3 anyway, with some unusual looking pickups going on that might have been rebuilt Bisonics and might have been something else.
Phil started off with a bone-stock Starfire II bass:
But by the time the Alembic guys were done with it it had turned into this:
The Bisonics are gone!