A couple/three years ago, Fast Larry did a header shootout with several top headers. I don't recall if Scorpion was on the list (and his site is down again, so I can't check), but Yoshimura, Holeshot and the Brock/Hindle full systems were. The Brock/Hindle system brought out the most in both a stock bike (with a jet kit) and a well-modded bike (head work, cams, high compression slugs, etc). The differences weren't earth shattering though. Unless you're looking for every scrap of power, I'd say go with the system you like the looks of.
Anyone know if Scorpion is still made by Akropovic?