Re: Pots for Phats?
I've got a bunch of Phat Cats myself. The neck definitely needs 500K's. I use 250K's in the bridge of my HB guitars (and HB's have a focus on midrange), and with a single coil, P-90 or otherwise, which have much more treble & clarity than a HB, so I think 250K's are required; you don't need to add treble on top of treble.
Now with Phat Cats we have to talk about the magnet issue. I'm a 335 man myself & the stock magnets in Phat Cats (twin A2's) leave something to be desired in a warm-toned guitar. Duncan baffled me on this one. The neck is strong and very dark, and the bridge is weak & thin, all courtesy of the A2's. The neck overpowers the bridge. Not sure what they were aiming for.
Once I decided to try some magnet combinations, things totally changed. I've put Phat Cats in a number of my guitars now. Love them. Getting an A5 in the neck gave a lot more treble & definition. I've tried A5/A2, A5/A3 (bright & chimey), and A5/A4 (ample treble with good mids), and all were far superior to the stock A2's. Really opened up the sound so you can tell they're P-90's. You can get 'bite' from them, that you normally only get with a bridge PU.
I didn't know what to do about the bridge PC, so I have several guitars with a HB bridge/PC neck, which is a very good combination BTW. Then I finally decided that the right magnets should be able to give me the bridge tones I wanted. I tried an A8/A4 pair, and it's excellent. The PC itself has an open, bright tone from being a single coil; the A8 gives high output and fills in the mids, & the A4 with its balanced EQ reinforces the tones. Now my PCB's are full & rich and yet raw sounding, and have enough output to balance with the neck. Just what the doctor ordered.
So, you can try a pair of PC's with the stock magnets & see what you think. May have the tones you want. If not, magnet swaps take minutes and since each one has a pair, you have many more potential combinations, so you can really dial in your tone, much more so than with a HB. If you're new to this and need help with swapping magnets, let me know. Since I started swapping magnets in them, I've become a big fan of P-90's and HB-sized P-90's. Hopefully they'll work for you too.