FWIW, my last three converters as the car evolved:
1. Coan 11" Pro Street spec'd for about 3000 stall (pretty close in my car); only had about 4% slippage, but Coan rated it for max of 500 HP, IIRC. Worked fine when car was low-to-mid 12s, then lost its sh!t when I put in a new engine that pushed the car well into the 11s

2. J.W. 10" 3800 (they offered a 3800 and a 3400 version); flashed about 4000, but slippage was 12% and it didn't drive well on the street... very "slushy"

3. Dynamic 9.5" advertised as 4200, IIRC; flashes to about 4500 in my car and slippage is about 8%; drives much better on the street than the J.W., and picked up .2 and 2 MPH as well because it didn't slip as much

4. Dynamic sold my friend Mike on a 9.5" for his car (the one I described in my previous response) and his experience w/ it was a lot like mine w/ the J.W. He switched to something much less track-oriented and was much happier.

"You pays your money and takes your chances".