I dont know if Art CArrs stuff is the best but Ive got one w/ full manual VB w/brake and 2600 converter and works fantastic. I recently took thecar for a 400 mile trip. Cruise rpm was about 200 more than w/ stock converter and gas milage went down maybe 1 mpg. Theres other good companies like Lentech but the local mustang guru who I got my trans from has one in his wifes car a twin turbo rocket (low 10s,still has AC) and has held up just fine. I would highly recommend
I have one of their AOD's in my car and it rocks. I have the manual/automatic VB with the electric OD delete and just use it as a manual shift. I swapped to it form a Tremec and love it.