Well, David uses a Dukoff Metal mouthpiece. Normally I don't preach equipment as the key to your sound, but that setup is a big part of his sound. Also, if you've ever watched him play, look at the neck angle that he has. It's almost like a clarinet mouthpiece position. When I need to have that kind of sound, I do have a more clarinet like neck angle. Also, you need lots of air to have a big powerfull sound like that. With all of that said, the BEST way to sound like somebody (nobody wants to be a copycat, but I found my personal sound by first sounding like Gerald Albright, Sanborn, Whalum, Cannonball, Desmond, and through that came my voice) is to LISTEN and play along with them. One of my favorite excercises is to put my Sax playlist (love MP3s, great for playing along) on random and just blow. I play a Beechler M8M and go from Take 5 to Cannonball to Snakes to Jonny hodges. I hate to be cliche, but think the sound and it will come out that way.....