Shocker! Britney Spears, who recently signed a Pepsi-ad deal, demands Coke backstage. Revealed! Christina Aguilera insists on Flintstones vitamins. Such concert riders are available for all to read at The Smoking Gun (thesmokinggun.com), the hell-raising site that’s widened its scope from pols and criminals to more celebs. Documents like an ‘N Sync lawsuit and the denied appeal of Foo Fighter Dave Grohl’s Australian drunk-driving conviction (all six pages of it) are becoming the site’s stock-in-trade. Why now? ”We’ve done things that tap into a more pop-culture-y vein,” says editor William Bastone, a former investigative reporter for The Village Voice. ”Those exposed us to an audience of younger people.” And yielded greater buzz. Part of its new approach, says Bastone, is to scrutinize the stars with ”techniques we normally use to crack down on hoodlums.” Sometimes, of course, there’s precious little difference between them.