Moving the rear caliper isn't required to track the Aprilia RS660, but it does make changing the rear wheel a bit nicer.
 
3.5 x 0.6mm fasteners allow you to bolt to the axle bolt and create a captive hanger for a no-fuss wheel change at the track.  Stock wheel speed sensor moved to the bottom under that axle and protected with a small lip to keep it safe from any wondering brake discs.
 
Works with or without ABS.  It does not work with stock brake lines.
 
THE CORRECT BRAKE LINE IS AVAILABLE HERE