16v indicates that each cylinder carrys 4 valve
But can any body tell me what for these no of valves are being used instead of 2 valve
Would this going to increase any efficiency

For engines to develop more power, usually needs to handle higher volume of fuel/air
Mixture, Also you will need to get rid of more exhaust. 4 little valves easier to fit in combustion chamber, than 2 big valves.