The Aprilia RS 660 is the clear winner when it comes to performance, speed and overall power. The Aprilia RS 660 is powered by a 660cc three-cylinder engine that produces a maximum power of 95.2PS at 10,500rpm and a peak torque of 67.5Nm at 8,500rpm. On the other hand, the Honda CBR650R is powered by a 649.7cc four-cylinder engine that produces a maximum power of 86.3PS at 11,000rpm and a peak torque of 62.9Nm at 8,000rpm. The Aprilia RS 660 also has superior acceleration compared to the Honda CBR650R. Additionally, the Aprilia RS 660 has a top speed of 250kmph, whereas the Honda CBR650R has a top speed of 240kmph. In terms of mileage, the Aprilia RS 660 offers an ARAI certified mileage of 25kmpl, whereas the Honda CBR650R offers an ARAI certified mileage of 22kmpl. All in all, the Aprilia RS 660 is the better option when it comes to performance, speed, power and overall mileage.