Stock 2003 Cobra Wheel Offset?

Short answer: I believe that is about right. I had +25mm offset.

Long answer: Its kind of weird. The rim width from outside edge to outside edge is more than 9". The true 9" width is at the tire bead. So the rims are actually a little wider than 9". Anyway the the offset is still +25 from the center on the rim.

Rogue Cobra

I just put a set of Factory 2004 Cobra wheels on my car and they had 26mm stamped into the rear of them, so you are correct.