I was reading about intercoolers here...

http://www.are.com.au/feat/techtalk/intecoolersMR.htm

...and it sais...

"A few factors should be remembered with air flow. Definitely don't polish the inside of tanks or pipes. An ultra smooth surface causes capillary tension on the surface layer of air with the wall & will increase drag so increasing pressure drop."

I was under the impression that polishing the inside of tubing and manifolds would result in less friction so more air flow. Not polishing the end tanks would allow for more heat dissipation but I believe the author is talking about the tubing as well. I did a search in Yahoo and most of the finds on capillary action deal with liquids although air can sometimes be considered a liquid I didn't see tension on a polished surface and could explain? How polished does a surface have to be for this capillary tension to be a problem to the flow?