Gaunty,
The Tays on the UPS 727's are rated at 15,700 lbs of thrust, the max weight of our 72's are 169,500 lbs. The higher bypass ratio of the Tays give us great economy and power, but as we climb into the mid twenties they really gasp for air, and the climb rate suffers. The good news is most of our flights are less than 1.5 hours so we don't need to climb that high anyway. Compare the weights of a 727 and a GV and you'll realize the difference in performance.