Low profile duct options

[nip]

I am renovating part of an unfinished basement and I need to replace 8 and 10 inch tubular ducting with a wall stack style duct. Only about 10feet of each, connected directly to the main discharge duct. What are my options for improving ceiling height by introducing a flat duct? How slim can I go? I am willing to install a booster van if needed. I would also be cool with exposed ductwork.
All I've seen thus far is the 3in wall stack at lowes.
Thanks in advance.

[hcong]

You can use rectangular ducts... the greater the difference between the base and height the more friction loss.

See link for round to rectangular ducts..

http://www.electromn.com/pdf/EC001.pdf