G harp's killing me

[Mark-Jason Dominus <mjd@xxxxxxxxxxxxxxxxxx>]

    I just got a Hohner Blues harp in G.  I was expecting it to be one
not higher than my F harp, which is pretty high already, and I was
pleasantly surprised when I found that it was lower than that, so that
it was a note lower than my A harp, which is pretty low.  I like the low
ones better.

But it's giving me a lot of trouble; I find it takes an awful lot of
wind to get the notes, especially the low draw notes, and I can't bend
some of them at all, because I just can't get enough air through.  None
of my other harps, not even the A, give me so much trouble this way.

How come the G is so much harder?  It shouldn't be so different.