Bright Flats for slapping?

I have a Jazz bass in my rotation that currently has flats on it. I definitely prefer the tone of flats but I'm slapping a bit more now and would like to change the strings to something not as dull.

Are there any flats out there with lower tension and on the brighter side making it suitable for slap or should I just find some duller rounds to suit my needs?

I'm not expecting fresh set of rounds level brightness (and I don't like that tone anyway). But something that's a bit easier and more pleasant sounding.