Yamaha R15 is a performance benchmark for the lightweight sport bike category of Indian motorcycles. The R15S has been launched due to the user feedback of uneasy riding for the pillion. You have two clear scenarios for choosing a R15. If you ride solo and very rare have a pillion, the R15 version 2.0 is made for you. It gets a sharp, more track based super sport approach and even comes with better tuning for the production of 16.8 BHP and 15 NM of torque.
If you are mostly riding double and still feel good while revving a bike, the R15-S gets a comfortable rear seat with grab-rails. It makes it easy for the pillion to cover more distance safely. The engine here produces 16.36 BHP and 14.6 NM of torque. The reduced weight of 2 kg balances the performance lag and R15 becomes the best option if you are willing for a 150 cc premium motorcycle.
R15-S is actually a better option as paying INR 500 more can bring more comfort to a pillion and won’t even effect your ride quality. The R15-S would cost around INR 1,28,000-1,30,000(on-road).
You can know more about the R15-S here - http://autos.maxabout.com/bikes/yamaha/r15/yzf-r15s