the Z. Did you use the factory starter or something else? I would be very interested in doing this myself. I track my Z about 3-4 times a year. Trans issues always come up. After about a year of track use I blow out 3rd gear and the counter gear. A T-56 would be nice. The extra gear would be a lot of fun at the tracks I go on. My second thought was the 5 gear PPG dog gear set (helical cut). Not the best solution but a compromise.