Fuel mileage in the mid-30's and more are for primarily highway riding in top gear 90% of the time or more. There can be a huge difference between city and highway fuel economy. All I'm saying is that I was left with the impression that most of your riding is in 2nd and 3rd gear in the city, and I assume a lot of stop and go traffic. If I got that right, then my contention is that you're already getting excellent fuel economy. If I missed the mark on your riding conditions, etc. then I stand corrected. Doing the cooling system and (I assume) a coolant flush, was a very good idea. Since you spoke of wear marks on the thermostat, replacing it while the radiator was removed was a good preventive maintenance step, but I am still dubious about it having any positive effects on your fuel consumption. Do you ever have the opportunity to ride a 300-400 mile day ride out on the open road? That will give you a more representative indication of its fuel consumption capabilities.