I have one of Bill Chapins' on my Chapin. I believe it is called "Bad Dog" - he winds them himself.
With the tone fully up it sounds like a great Strat P'up (it helps to knock the Volume back to about "9") but with the Tone down to taste and the Volume full up it is a P90.
My Chapin is like a Strat but with true Gibson scale length - the "Bad Dog" is the bridge P'up. It has it's own tone control whereas the middle doesn't btw. I can get a credible Les Paul Jnr sound with this guitar. All the P'ups on this guitar have different spec's - you can see this guitar towards the end of the massive Chapin Guitars thread, it is the Fiesta Red one called: "Hankahoula".