my '13 does the same thing from day one, if i pin it in high, it will go to about 7200 then once i get to about 35-40mph it will drop down to about 6900 and then slowly rise back up as i get going faster, when it drops ii can feel the motor get out of its power curve and there is a noticeable slowing of acceleration, im in the process of installing a VFJ primary and hope that will help with the problem, i run stock size tires with a full muzzy and a PC5 w/autotune