just to let everyone know, the A16 header flanges is available in 5/8" mild steel ($60) and 1/2" stainless ($80), the same prices same as the T20/T22.
http://www.postimage.org/aV1mE0hS.jpg http://www.postimage.org/Pq1LRZ7J.jpg http://www.postimage.org/Pq1LS0CS.jpg
enjoy! ;)
Garrett