I used to always mod my instruments in my teens and 20s - putting a Precision pickup on a Jazz Bass, EMGs on a Rickenbacker 4003, Seymour Duncans in my Jazzmaster (although that was a swap, no mods needed), installing a pickup selector switch on the same Jazz and then changing it to a blend knob. It was a popular thing to do in the 70s and 80s, I stopped all that in the early 1990s. It just dawned on me: "Do you really think you know better than Leo Fender or <fill in the blank pro designer>?" I'm now kind of mortified I ever did those things....especially to that Rickenbacker. Presumably it's still out there somewhere.
Although I did swap out that old Precision pickup in the Jazz for a Bruce Thomas from Bass Centre a few years ago, so I guess I can still be persuaded.