Have a look at this guys.
I run a toyota A340 4 speed auto (supra auto), modified, manual shift.
I also run a lock-up converter with increased clutch area. The converter is relatively small as the motor I'm running is 4.5L, meaning it has good bottom end torque.
The below graph shows 2 power pulls, done back to back, with the second one done with the lock-up in the converter activated.
It pulled an extra 10kw, but if you run a bigger converter, that number will be bigger.
Also, consider that in std trim the clutches are not meant to hold a motor at full power, so increasing clutch area and line pressure is adviseable.
Ultimately I plan to try the lock-up out in the deep end of the track for extra MPH.
Cheers
Sean