While I am not disagreeing with Ron because technically he is probably right, they are "claiming" performance gains. But most likely the "performance gains" that Saleen is claiming is due to the 98mm MAF that it comes with.
Personally, I ain't drinking the Koolaide just yet. A conversion kit has got to cost at least a grand if not more for existing customers. No telling how much they want to slap on to the cost of a SC for new customers. And I do see some "issues" with it, such as the air filter being basically right in the intake opening. Rain is gonna fill that airbox up nicely. Also not completely thrilled about yet more plumbing and wiring changes.
Don't get me wrong, love my Saleen SC. I am making a hell of a lot more power on less psi and timing than most. But if they want to impress me with an upgrade of some kind, how about figuring out a better idea for the alternator so that you don't have to pull the damn thing off to replace a belt. Makes trackside pulley changes kind of a pain in the ass.