I have used the Transpak in the past. I had it in my own car along with a few other mods for a few years. I was happy with the kit. It gave a hard shift and had no problem chirping the tires from 1-2 and 2-3. I have recently started using the TransGo kits. I do like the Transpak because it includes a new main pressure regulator. This is commonly worn in the C6. Hope this helps.