Rahul, Instead of Shifting 1.6 to 1.7 K shift at 2000 RPM, when you change the gear at 2000 RPM, It will drop in 1600-1700 RPM, so you will get power on the Power band. Say, you are shifting gear 3 to 4, in 3rd gear punto will reach 2000 RPM at 40KMPH, so same time if you change gear to 4 then at 40KMPH you will be on 1600 RPM, you will not feel lag. If you shift at 1600-1700 your RPM will drop to 1100-1200. From 1100 to 1700 you will feel lag. Try to use this and check the milage.