how much boost do you have. i saw with other speedtech setups that till 30-32 psi there is no problem. (ADV backpressure 35 max.)
It may have started after bringing the boost up above 30psi or so, but happens even at 20psi now. Also, bank 1 and 2 were off by about 0.8, with bank 2 reading lean. When I pulled my plugs, bank 1 was clearly running lean and bank 2 was not. Have new sensors on the way. Are you still running the ADV? Are you happy with them still?