I have the Vintage bridge on my KBP5 bass and i think it is what helps it growl. .where many P bass 5's do not growl... they thud.. Thud is cool. but i like a little growl with my thud and mids that poke trough..
For the stuff i do i need the more vintage type tone that is brighter with good mid punch like a 60s bass does..
Its not your mudd machine.. Infact i did a gig last night with my Sadowsky NYC PJ5 passive P only, and it is a great bass.. Incredible bass, switched half way through the set to my Alleva,and the kbp5 just sat in the mix better. And did not get into guitar freqs by overlapping the freq area,but was clear and smooth they way it should be ..
The Sad is still with me all the time..
On the Alleva kbp5 i feel Alot has to do with this real light alder body for tone and sustain, the DN fingerboard really adds snap to the top and attach and the bridge brings out the growl.
A friend Lanice Morrison plays the same bass with Mike McDonald. Same color.. after he saw mine he wanted one from the same piece of wood... he has the B bridge and the basses sound different.. but its mostly in the attack not the decaying note..
the attack with the Vintage is pointier and the attack with the B is wider.. and there are still many other variables too.. but overall either way both sound great...
Can the audience tell the difference .. probably not. but you can when you play it.. it feels different.. not better just different.