I doubt I could make 500, but 470-480 would be doable. I have 205's in the car now and they flow great for what I need. 225's, an Ms4, and a fast 92 could get it real real close to the 500 like you said. I do think anyone making 500 in an auto is on the very edge of drivability.
Edit: I think I see what Scott means. Yes making the power is doable but not in a "street car". Put an MS4 in a car that makes 510rwhp and I bet a car with a baby cam still beats it at the track. Steve, dont make a 500 hp car that runs 12's when you can make a 440 hp car that runs 11.5's.