BRZ FA20 Running rich past 6000 rpm

[plague]

Hi All,

Have a weird issue with my Turbo BRZ, it has the AVO turbo kit stage 2. When doing a WOT run the wideband (LM2-wideband) reports that it is about 6% - 10% too rich past 6300 rpm. It dips to about 9.5 - 10.0 AFR.

I have already pulled 10% fuel via the map sensor scaling table. But the car is consistently rich past 6k rpm.

I have a brand new bosch o2 sensor (as I thought the sensor might be the problem).

Boost levels are at around 8psi to redline and everything else looks okay.

I've smoke leak tested the car and recently just changed the DI seals and replaced o rings etc.. for the direct and port injectors. Maybe there is a leak?

I can't understand why the fuelling would be fine up until 6k rpm and then suddenly run rich.

I've attached two images. The first is a WOT run with the brand new o2 sensor. The second is after I've made fuelling / MAF adjustments.
The car has been running this same setup for 2 years and the issue is only appearing now.

This has been happening for a while and thanks in advance to anyone that might be able to help.