A904 Lock up performance build

Sorry to intrude, but what's wrong with a lockup trans/converter for performance? I really don't know much about transmissions so this is a real question.
I need a stall to help launch the car and this one locks up pretty tight at about 1100 rpm so the car is a bit sluggish out of the hole. It would be fine for mild street driving and cruising. I am not finding anything about a stall converter that actually locks up, but I am learning as I go with this project. I have the tranny apart and the shift kit nearly completely installed but need to determine a few more mods that revolve around the lock up aspect as per my questions asked above.