This was my first pick up replacement. I replaced the stock pickup in my old Warwick PJ with the SPB-3.
Seymour Duncan includes a manual with the electronic schematics for this pickup, which made the installation a lot easier. These pickups are meant to be a drop in replacement for any Fender P or PJ bass. In my case, the replacement wasn't exactly 'drop in', as Warwick uses other dimensions, materials, and designs than Fender. Especially their use of a spring instead of foam underneath the pickup made this a little bit challenging.
The sound however, makes this all worthwile. The output is almost at twice the level as my stock (MEC) pickup. It's very ballsy, very low end articulated, fatty, and maybe a bit under represented in the mids. As the wood in my bass make for a particularly mid heavy sound, this works out well, but it is something to be noted. All in all, do recommend!