you can certainly see the familial resemblance.
The rear doors on the 03 are longer than the 05's. The whole car looks ever so slightly taller in the front, and longer overall.
The 03 looks nice, but I am not sure how much more of a quantum leap the 05 could make without becoming a truly different (and different looking) car.
I checked out a RB GT 5MT in Omaha last weekend, inside and out (didn't get a chance to drive it, but did start it up...) and now I really want one badly.