The Superbike's windblast blows me backward into a fellow marshal. "Pretty crazy, aye?" my comrade laughs. All I can mutter is, "Holy shite, he was close!" Other riders follow at 10-second intervals, displaying varying levels of ability, boldness and control. Some 17 minutes later, McGuinness rips through on a flying lap. Now running 175 mph, he carves an even tighter line. Then it hits me: I could be _killed _doing this!