Which type of fuel are you using, race or pump?
Have you ran it leaner to find out what is to lean? If not, why not
I know that all systems, O2 and dyno software, are not exactly the same so what I have seen on other motors does not make it the same as yours, and visa versus
I've always went richer first, at the track or a on any type of dyno,chassis or engine, and then went the other way on the tuning and mixtures and I made sure of where the happy spots where on jetting and timing as well as when and where it would start to loose power, up or down