Narrowband suck, I don't even trust them one bit. At one point I had .930-.950 O2's and when I got a wideband, it actually showed low 10's and high 9's in the AFR. I leaned it out into the mid 11's on the wideband and what-do-ya-know......O2's at .930-.940.
Get a wideband if you want to get WOT fueling where it needs to be.