l was reading a lesson on the net and it said that a wide arc on the up and down swing will help gain speed but sergio garcia has anything but a wide downswing,, do they both work?and also,, wat kind of grip does sergio garcia use?

Wide arc means that u take the butt of the club as far away from ur head as possible on the backswing. It is not how far back u can take the club.

To create a whip-like action with the golf club, try this:
On the backswing, keep the butt of the club far away from ur body & maintain ur balance. On the downswing, try to do the opposite & get the butt of the club close to ur body without losing ur balance. This creates a lot of lag & it will whip the club right through the ball.

Lag increases clubhead speed by whipping the club through at impact.

Actually if you perfect this move you will create enough down force to where you will get more spin on your irons. But it will increase your distance because you will flick your wrists at impact and the rest just falls in line.