Re: Phat cat vs Prails ash body
I prefer the P90 tone from the P-Rails to that of the Phat Cat. I'm not sure if this is the case, but part of that might be that the coils are narrower, like a real P90, and that the coils can be placed farther out toward the edge if the humbucker rout, so you get them a bit closer to how actual P90s are traditionally placed.
P-Rails also give you the option of adding a little boost by bringing in the rail in addition. If you don't want to wire the rail in, then you don't have to. But it's there, if you ever want to.
This being said, two things: 1) The only P-Rails I use are the neck versions – in both neck and bridge positions. I find the bridge version to be too heavily wound. 2) I opt to orient my P-Rails such that the P90 coils on both pickups are closer to the bridge than to the heel of the neck. This gets the P90 coils as bright as possible, and the rail coils as warm as possible.