I have the Rush Exhaust as well 2.50's and at 70 with my windshielf up I feel the drone. Yesterday I did a 200 mile ride and one streatch was 1.5 hour streight at 70 when I was done I felt like I just walked out of a rock concert. I was also wearing a full face helmet and my windshield was full up.
What are the specs on your rush exhaust.
thanks