The shortest possible answer is... The exhaust pipe determines the power band. A good pipe set to 8000-8500 rpm's will get you 50mph top, and 45 all day cruise. Your pipe stops at 7000 so running above that rpm just makes heat, and no more power. So at 7000 rpm you do 40ish... with a good pipe you can raise the cruise rpm, and the speed.
..there should ever be a better short answer??...heh??...