I have two 3/4 in. pipe nipples, and 2 ~3/4 in. vertical pipes. one w/ ball valve. One with an elbow... This past cook, I actually blew air down the pipes with a pump, for some reason it does (at least for mine) inhibit air flow. The pipe nipples, because its short, more air definitely goes in. I proved this on MY UDS by closing all vents- opening 1 pipe intake, let UDS run...then closed all vents and used 1 PIPE NIPPLE air intake, temps rose about 20 degrees higher.
Anyways, thats MHO!!
To Eternity and Beyond!
BBQ Brethren 22.5" WSM (1,000,000 post mod.)
Weber Performer (169.00/brand new mod.)
Weber Handles from www.amlwoodart.com
22.5" Weber kettle, (refuse collector mod.)
18" Weber kettle (almost new craigslist $20 mod)
"crest of a breaking wave" thats my name...