After a some studying wiring diagrams, selecting and receiving a push-pull pot I finally got the series/parallel wiring wired up on my J Bass yesterday. I always like this bass, especially with the Aguilar AG 4J-HC pickups. And while a good sounding bass, there were times when I wanted it to have more cojones in the sound. I think that is the draw of the P bass. Having never owned P Bass I can't tell you how close the sound is with the series wiring, but it's deeper, for sure in series mode. But with the switch I didn't lose anything in parallell either. The parallel wiring sounds the same as it did before, with some brighter crisper sounds, but sometimes a bit too bright with the tone all the way up. The series adds volume and thickness and has just enough brightness with the tone at 100%. This new wiring gives me a 4th gear in tonal pallette selections, almost as if it were active. While I really haven't had the desire to bring my Jazz 4 out to play and relied on my 5's, it will get some serious consideration (if gigs ever open up again). With such a simple mod, why don't more folks do it??? I can't believe I hadn't done it long ago.