Thanks for the feedback. Badly needed here!

bigtopsfinn, what make you think that it won't work? I respect your opinion and I am certainly willing to believe that it won't work but I'd like to confirm with facts or at least conjecture . Considering that it is possible to reduce from 6" to 4" why not for 4" to 2"? I realize that there are significant volume differences between 4" and 2" but enough to make it unworkable? What about my idea of using a speed control unit to adjust the air flow? Perhaps it says something that there are no reducers going from 4" to 2"?

stra8outtaWeed, I'm not sold on the LEDs. I've read very mixed reviews. I like the proven technology and results of the HID. I'll do some more reading. Concerning odor control, I have considered other options. My situation calls for 100% reliability. I have to be able to have very uptight work colleagues (including my boss and his boss) directly upstairs on a regular basis. I suppose I could do an internal filter and odor box but I'd MUCH prefer to vent everything out doors.

You raise a good point about fan noise. Can anyone comment on the noise level of inline fans?

Thanks guys. Keep the comments coming.