I happened to find the site below and felt the author a) knew what he was doing and b) validated that he knew what he was talking about with his results.
I thought others here would find it very interesting.
Also, don't miss checking out his home page as there is other cool stuff.
Enjoy,
Steve
http://www.veglisteroidnz.co.nz/veglisteroidnz/10_hp_petteroid.html
How about a flag pole made of hollow pipe and use it for an exhaust stack?