I know thet the 65's were ported differently for '03 to present with a more aggressive exhaust porting, but I'm not sure how that would affect the pipe. Maybe the tuning would change. I'd check to see if the stock pipe is the same for both models. If so, you could obviously use the same aftermarket pipe.
Does FMF list a different pipe for '03 to present? Maybe the listing you refered to is outdated and simply didn't cover models that weren't in production at the time of printing.
My experience here is simple, I do have an 02 and an 06. My son was riding the 02 one day and did major damage to the silencer core. I ended up buying a ProCircuit pipe and silencer, later deciding to put it on the 06 bike. I then put the stock 06 silencer on the 02, and it fit with zero difficulty and I don't remember changing the pipe. It was over a year ago.