Getting your clubs fitted by a professional is essential to a great game. But don't alter your current clubs to make them longer or shorter.
Lately I've seen amateurs add length to their drivers on the theory that they'll get more distance. That just won't work out too well. The shaft of your club and the club head were made for each other by the manufacturer. Adding length will simply ruin your club.
The best way to add distance is to work on your swing!