ok i got a few questions about my hx40. i have the 7 blade 60mm inducer. works good i was wondering ive been told the 6 blade 60mm is the best and that the whistle is really loud!! also there are few different sizes of exhaust wheels to choose from and wondering what the differences of them are? and also been told the exhaust wheel size and how many blades it has also determins the loudness of the whistle?? if yall can give me some input thad be nice.