If you are tuned for the CJ65 you can run our Twin Jet 67mm with no tune change. Just bolt it on and pick up 10-12 rwhp over the 65 and 20 over the stock 60.Is a 67mm close enough to a 65mm Throttle body that the tune isn't going to make that much difference? Thats what I am being told......if so fine but seems off base.