No the stock cv would be better, it’s much more forgiving on altitude than the fcr mx. The fcr can be finicky if you go through huge temperature swings and I would imagine it’s the same for altitude. but once the fcr mx is dialed in there’s nothing better. although after running the true high compression piston I think I agree with Steve that the high comp piston is the better mod if you had to choose one. She feels alive now, and the low end torque is much better.