I put a Badass bridge on my Jazz Bass that I had a few years ago, but that was a recent Mexi JB, and I sold it anyway. Whatever sound change the bridge may have done was not something I could really pick up on at the time. Waste of money, but in those days I was convinced that "TONE" was the almighty point of pursuit, and if I had the right tone, I would sound good. I still have great appreciation for an instrument with a nice tonality, but its near the bottom of the list for me these days..."tone is in the fingers" is a bit of an oversimplification, but there's some truth to that. I'd rather listen to a good player on a mediocre instrument than a mediocre player on a great instrument...and I've met a lot of the latter and I was certainly guilty of being one of them in younger days. Buying a Rickenbacker didn't make me sound like Chris Squire, nor my earlier (and ill-advised) attempt to sound like Jack Bruce by trading my cheap P-bass for an Epiphone EB-0. The EB-0, with its short scale and single neck pickup, was in retrospect a much worse sounding (though admittedly significantly prettier) instrument than the cheap Epi P-bass copy I let go. I'm such a sentimentalist, that's the only guitar I've ever sold or traded. And weirdly enough I miss it from time to time, if only for sentimental reasons.
Lately though this bass has been getting all my attention:
Gary Willis model, strung with groundwounds, custom bartolini pickup. I don't own the bass but am borrowing it, and I have to say its the sort of instrument that makes you sound better than you otherwise would. I'm normally a 4-string, passive, fretted bass sort of guy, to the point of using my Rickenbacker on funk tracks, but I love this bass....playing fretted now feels extremely restrictive.