From there site (The black PVD material looks like black chrome)
http://www.pvdcoatings.org/l
http://www.corsaperformance.com/blacktips/
I will install them at home, Right now I have flowmasters with cats. I have to pass Ga. emissions first and one more time next year. Its not to much trouble just to swap them out. The flowmaster set up is welded so its one assembly I will do the same with the Corsa. Just want the extra HP the Corsa and no cats offer.