I run a transmission specialties converter that started out as a TCI. I sent it to TSI and they upped the stall to 5800 from 5500 and my car picked up .2 in the quarter.
I had a hughes spragless that was 6000 stall and was .3 slower than my faithful TSI converter. I tried a buddy TCI 5400 stall off the shelf and slowed down .15.
I guess my best suggestion is to have one built exactly for your application, it does make a difference.