Since the narrrowband is unreliable, it's kind of hard to say what kind of AFR you are running compared to your O2's. When I had the same mods as you I had to run a 3.5 pulley and my O2's were around 955 to 960. Last time the comparision was made on my car that was an AFR of 10.6 (pig rich).
With my XP, headers and a lot of other things, I can only run a 3.25 pulley KR free with an AFR of 11.6 which is ~910 iirc.