Its a fairly good intro...
Yeah, I'd definitely have the music cranked a little more and maybe for effect, have it playing one kind of music before the shooting and maybe something really heavy afterwards. Myabe have a little more than just gun shots like melle or just plain hand combat before the shooting scene. For the shooting scene in an opening, sniper doesn't cut it for me; something more bloody and noisy like a shotgun. Also, have the title slam out at the audience. The audiece is expecting action if the title looks like it is going to jump out and kick their behind then you know it is good. Good luck in the making of it!