These are good value quality pickups. They have an incredible air, the top end clarity is outstanding and at the same time they have a great bottom. They're meant to be voiced with a modern scooped sound, great for slap, etc. The problem is that they didn't work well with my all-maple neck-through, a combination with no midrange to speak of.
In the end I swapped them with Dimarzio Area-Js, which are awesome pickups!
I suspect they would work much better with typical jazz basses that use warmer woods.
Also, make sure they will fit your existing pickup cavities.