What if I were to have a higher output pickup in the neck rather than in the bridge? Would I just need to adjust the bridge pup to level things a bit?
My understanding is that you commonly want a higher output pickup at the bridge because the strings don't move as much there, and a higher output bridge pickup balances naturally with a lower output neck pickup (since the strings move more at the neck).
The pickup descriptions on the main BKP pages are, as I understand it, primarily describing the bridge pickup specs. In a calibrated set of Riff Raffs (for example), I think the neck pickup is a slightly different creature from the bridge and would likely be of somewhat lower output. But the BKP wizards will steer you right on this sort of thing.
I just really like the sound of owning a Warpig :P
Well, I hear that! The feel-good coolness factor certainly works its magic on me. :)
More realisticly... what would sound better out of a Riff Raff brige/Mule neck and a Mule bridge/Riff Raff neck?
That, I guess, depends a lot on the kind of tone you're looking for! I don't think I know enough about the subtlties of the Riff Raff vs. Mule, but my gut feeling would be Riff Raff bridge/Mule neck if you wanted to mix'n'match those two. But that's very much an uninformed opinion! Again, the BKP dudes will have the info you need. :)