I have done this.
IMO, you get 1 good sound (parallel) 2 other crap sounds (series & single). Not worth the effort.
Also as far as I can tell, the bass was originally wired in parallel, not series (contrary to what was said above).
Not sure why or how.
My SUB SB4 (Sterling body shape w/1.5"nut) sounds like it's wired in series. I actually prefer the series tone... over the parallel tone.
I would expect the SUB Ray4 to be wired in parallel for the traditional "Stingray" sound.

