http://www.transmission-specialties.com/ These guys are good to work with I have had good to excellent results with a street convertor that did exactly as promised. A close friend has been using one of there spragueless convertors behind his 540 BBC trans brake combo that runs in the eights. He too has been very pleased going on 6 years with no indication of needing refresh. It has worked as promised also. FWIW they also manufacture components for other convertor companies.
I have also had Turbo Action convertor that flashed 5200 rpm on a 4400 rating but was well coupled through the lights, A POS B+M and an old Fairbanks generic 10" back in the 70's that left a lot to be desired.