I just finished rebuilding mt st165, I finally got my prosport wideband installed and I am trying to understand my afr readings. I have q jdm engine, stock ct26 running 15 psi, New everything on the motor prosport boost gauge, walbro 255lph fuel pump, straight intake and a 3" Aussie Dp. When I'm cruzing it reads around 14.7 under max boost around 10.0 and when I let off to slow down its reading 20.0. I did have some problems with my last maf, maybe I need to adjust the new one.