Personally I skipped the output shaft because I don't plan on ever running slicks on the car. Yes the output shaft can break but only under extremely hard launches. Chances are that if your car isn't gutted and trying to dip into the 10's or pulling some crazy low 60' times that you're not going to come close to snapping an output shaft. Spend the money in other areas that will help with the longevity of the trans.