Many golfers are looking for a little more power off the tee and a lack of flexibility is often the biggest thing holding them back. Poor flexibility creates a shorter, steeper swing, which isn’t conducive to good driving.
To create a better turn, try turning your left foot in towards the centre of your stance a little at address. This will free up your hips, allowing for more rotation on the backswing creating a more powerful, and shallower, swing.
A great drill to get the feeling of generating more speed is to turn the club upside down and swing the grip-end as fast as you can. As there is no weight to hold you back, this gives a great feeling of releasing the club, which will deliver more clubhead speed.