A lower-profile tire will tend to deform from a round shape more than a higher-profile tire with the same load since there is less material on the tire to flex, so higher pressure is probably a good idea in general for lower-profile tires. I'm running 205/50/16" tires (you're probably running 205/45/17") rated for 44psi max, and I'm actually running them right at 44psi -- that's a bit on the high side, but I find it provides crisper handling, and noticably improved fuel economy. The main drawback with higher pressure (and the reason why most cars don't come wtih higher pressure stock) is more road noise and a bit stiffer ride. I would suggest running the pressure as high as you feel the ride is comfortable at, or up to the indicated pressure on the sidewall of the tire.

Also, remember that reccomended tire pressure ratings are for cold tires, so fill up sometime when they haven't been driven on for a few hours.