A narrow band gauge is telling you what the O2 is telling the PCM. At WOT the O2 pegs out at rich because the PCM is not reading it anymore, it is relying on the fuel tables. You could be lean and the narrow band will still be pegged at Rich. It defualts to the far right (rich) side at WOT. I think Autometers website might even say that. Let me look around....

 

Read this:

http://www.honda-tech.com/zerothread?id=1001592

If I remember right it may even mention the "Rich" condition in the instructions with the gauge.

 

I have a narrow band o2 and it was the biggest waste of money. Kind of like a throttle body spacer. The guage is good for driving me nuttttts at night and it good for the pretty lights. Narrow bands arent good for anything. I could keep going on and on about these things but all i have to say is: Narrow bands=