A good 10". I had Paul at turbo action redo a TA 10". I make 818ftlbs@4800, he had me give him the numbers off my Turbo Action 10", he said it was one of his good ones. I also had one of his 8" convertors but he said he wouldn't ever be able to get it right enough with the torque I made. Sent in my 10", it works perfect and he said it would handle 1000 hp.