I have owned a vn1500D since 1997 and 77,000+ miles, and am looking at the 2000. My question is what kind of mileage can I expect? And has anyone changed the final ratio to lower the rpm at highway speeds? Does this improve mileage? The 1500 gets about 37 to 38, which leaves me a little short on range with its standard 4.3 gallon tank.