I think your starting to get the order of things.......100% showroom stock = Production.......Any mods of any kind = Modified. If the stock bike has no streamlining.......OK.......but add a windshield and your in PS...Partial Streamlined. If your going to actually enter a class, you should study what is allowed to be removed or altered.......ie, signals, lights, handlbars etc. Also be aware that you have to have the correct or better 'speed-rated' tires for the existing class record.
Have some fun at 175 (maybe) on the Mountain Course..........then you can move to the 'Big-Boys' course.