niko86

to me it looks like it is pulling timing from 5k upwards due to the fuelling

did you log your timing values?

this could either mean the fuel compensation map needs some work or something is wrong (leakage after the MAFs, MAFs dirty, Widebands faulty etc)

i would recommend doing a dyno pull while logging MAF voltage, ignition timing, fuel corrections and AFR on both banks

btw
synolimit, the graph from saturday is the one where it is making less power, the stock graph is the one where it is way to rich (11.4)
so your theory might not apply here, since the less power graph shows AFR values between 12.1 and 12.5, which is too rich, but nothing that would justify a 10 HP difference