I've a Ric 4003, has two single coil pups with a separate volume and tone pot for each pickup. When both pups are on, it is a parallel pup circuitry. I'm aware of the ol' rule of thumb, use 250K for single coil, 500K for humbuckers. I'm guessing that is for the more critical tone pots? Anyone ever has any issues using 500K pots in the volume position for single coil pups?