@ schred : bro , kindly do not comment if you do not use EMGs , play bass or are very very familiar with the bass as an instrument. instead of contributing postively , it ends up a negative externality as the element of confusion is included in your recommendation.
for pickup change (if you are really interested in a pickup change) the key thing is to measure the pickup brackets/ pickup sizes. basses are not like guitars where generally a humbucker and a single coil pup are pretty much standard regiment size. bass pickups vary from manufacturer to manufacturer. the key thing you ought to note is the dimensions , following which you shortlist models that are suitable to fit your bass ( if no such models , tough luck bro , u might need to order a custom shop pickup with special size covers )
you might also take ur bass down to yamaha or any good guitar tech to inspect the pup coil windings. if your Bbn4 has been intensively played over a long period , the coils may need rewinding and "re-magnetising" if i m not mistaken.however this shouldnt be the case as the bbn4 is a relatively new model if i m not mistaken.
i know i dont know very much. but i hope the little i know helps :weedman: