I'm currently playing an E11 with a B45 mouthpiece and a size 3 Vandoren reed. My band director believes all the clarinets should be playing on a Vandoren 3.5. I've bought several boxes of 3.5s and none of the boxes seem to work well on my instrument. The sound is really airy and it takes a HUGE breath just to play through a measure. I can't seem to break them in, no matter how hard I try. I've even soaked them in water for several hours but none of it seems to work well. I've tried it on the same mouthpiece but with my plastic Vito clarinet I keep for marching season. Still the same problem. I read somewhere that the reed size actually depends on the mouthpiece. Is this true? I told my band director about my issue and he suggested wheedling the 3.5s down. He talked about bumping up to a size 4, too, thinking my mouthpiece might be rejecting half-sizes. What's your opinion on this? I could really use the advice - thanks!!