My setup: Selmer wooden bass clarinet (to low C) purchased in in 1991 with a Bill Street #4 (facing) mouthpiece with a Van Doren Java tenor sax reed #2.5.
I went through many mouthpieces (C*, D, B45, etc.) at great expense but always felt like I was "fighting the instrument" (never felt comfortable, always felt sharp with a pinched tone) playing it in a local professional Orchestra.
10 years ago a friend of mine recommended I try a Bill Street mouthpiece....she was using a 2 or a 3, which I tried but wanted a larger opening.
I purchased a "4" and it totally opened-up my sound; centered, dark, big, and even through all registers. The mpc also is a bit "lower pitched" thus I do not have to pull the barrel out a mile (or so it seemed).....plus just about every new reed I use "works"!!!
I am so enamored with the mpc that I actually purchased a second one (similar facing) and store it in a safety deposit box at my local bank - just in case my house burns down.........Mr. Street is elderly (in his 80's now) and still making mpc's, but no one lives forever...