gonna let ya'll in on a little secret... stainless steel cracks. unless you have massive support on the headers its gonna crack. i made headers for mustang svo'* for a long time, and the ss finally bit me in the ***. everyone was complaining, so heres how you do it, just to let you know... between each of the primaries, on the flange, cut the metal. it will basically look like 3 separate flanges, but what it does is let each primary expand and flex independently, but also be sure to use supports wherever you can.