Precision v Jazz Pickup in a PJ - what Kohms?

I'm pretty new at all this and I'm doing a budget rebuild and converting a bass from a 4 string precision copy to a PJ5. I read somewhere that one of the issues with PJ is that there tends to be a drop in the volume when you switch to the jazz pup. Based on what little research I've done, is this because the jazz pups tend to only be 7kohm whereas precision pups are anywhere from 8-11kohm? Should they be equal or is the difference expected or needed?