TKO 500 5-Speed: Rated for a continuous 550 HP and 500 ft/lbs of torque, this gearbox has a low 3.27 1st gear and .68 5th gear. This is the most popular choice for the 1981-1993 XJS HE which has a 2.88 rear-end ratio. The low first gear gives dramatically better acceleration without changing the differential ratio. 5th gear is excellent for low-RPM cruising above 70 mph. Top speed is increased.