Not sure when the V-Rex got the Rad-Loc. My 2000 Tailwind doesn't have it, either but, of course, my '08 V-Rex does. I have replaced the stock seat pads on both with the lighter, thinner seat pad/cover combo and like that better. A new seat pad/cover and new mesh seat back is much cheaper than a complete Zephyr seat; you need to figure out whether or not the Zephyr seat is worth the cost. You could contact RANS to find out how old your bike is based on the serial number. They could answer your questions about fitting a newer seat, too. Lighter wheels and tires never hurt uphill performance; have you checked out what Hostel Shoppe and other dealers carry?