I have a 65 GT Fastback with the 289/4BBL carb, roller rockers, crane cam shaft, it can get around 300 hp. The only problem I have is the C4 automatic transmission. #1 it doesn't shift fast enough and #2 once you are in 3rd gear you can't go over 70mph without going over 3000rpms. I was thinking about getting one of these "High Performance Automatic C4's" http://www.performanceautomatic.com/transc4.htm and was wondering if anyone else bought one of these or could tell me if its going to solve any of my problems? I dont want to covert to manual because I live in a city and it would be a pain in the ass to have to shift every 5 seconds during traffic or city driving.