@MovingPitchers I believe, at least in the electric guitar world, 250K is for single coils while 500K is for humbuckers. If you run 500 with singles, they won't be as bright and can be muddy and not in a good way. So, I would think that a 500 for a bass single (even though the P is a split single) would maybe give is "bigger punch and bottom end".
Great, now I've got a reason to order a quantity of 500K pots... Of course, I do have a Fender blacktop (humbuckers) and I'm sure those pots are 500.
Well, a P-Bass split-coil is essentially a humbucker, hence the fattier and punchier tone compared to single coils and I figured to give it a little more juice, a 500K would do the trick.
Hm. No wonder my bass has a lot of low end. I've been trying to dial in the perfect amount of high mids and highs for weeks but eh.