for all that people with a 2 pc doolin:
try any kind of mouthpiece. i´ve tried a red generation C (YES, C) in the D doolin and it sounds very much better. the conclusion: the doolin fipple is a holy 
Well, I acctually think the Doolin fipple has its own charm. It’s extremely pure, and extremely quiet, at least the one I have. Granted, it’s not the whistle I prefer (at all, I would never bring it to a gig of any kind), but as I said, it has its charm.