Ok, I just got off the phone with Borla and it will fit an '03 no problem.

-***- HEADS UP -***-

If you want this exhaust now is the time to act!!
Borla is discontinuing the cat back Xterra exhaust!
They have 4 left in stock and are selling them off at $333.44
You can't come close to that price at any distributor I have looked at - only direct from Borla.