I'm running the Michelin Pilot Sport 345/30-19 on the rear and with the stock 3.07 gears it results in an effective 2.94 ratio. With the 3.73s and the 345/30-19 tires I'm effectively 3.58 (or so) and I love it. It does not just spin, it accelerates great and does not make the car hard to drive or annoying on the freeway. excellent mod.
That guy at Palmer is an idiot, don't listen to him.