Re:Hitachi feature tool -
I haven't tried setting any of that stuff up. Seek noise doesn't bother me enough to make me get of my butt and do it.

maybe in the future.
Re: Fan
The grill at the back is 92mm vs my 80mm fan. But using a 92mm fan would probably mean greater air flow for less RPMs. I don't know what difference it would have if the fan was not directed right at the HD. But anyway, maybe something for the future if I get the urge again. (and the time).
I had a look at some of the muffler info. Seems to require a lot of room/space. I guess turning the whole top 3 bays and section of the case into one big muffler/wind tunnel is possible, with everything (fan, HDs) mounted inside along with insulation foam/material. But designing acustic 'filter' sections is probably a bit beyond me. (And they consume a lot of space from what I saw.)
--
Simon