The general consensus is that Level Ten has the kits that work-when properly installed. The 5th gen SS tranny is very different from its predessors and should be redone in a very clean place among other things. I think this is one reason wqhy there are few suppliers let alone shops that work on them. Also remember that there is evidence that even with an upgrade the tranny will not take a lot more HP than it did stock-it will shift quicker if done right. You can contact B&M, they are one of the oldest in the tranny mod business and see if they have anything.