Black Spirituals
https://www.youtube.com/watch?v=CJFfeEt35Bs
It seems these guys from Oakland have been around for a few years but they only came to my attention last October when I saw them at Cafe Oto. If Thurston and Lee's improv records are your thing then I would strongly advise you to dip in here. Super duper next level shit, some of the highest level of improvising I've ever seen. There was staggering depth and sensitivity in their playing.