It is amazing the difference in IAT's in different setups. I have the same setup and see the same IAT results as the op and I'm also trying to decide if I should do anything.
2011 SS IOM Vert. ECS Vortech 13.5 psi, Water/Meth, 125 shot, 2800 stall, LT headers, Zex 125 shot, Drag radials, Drag alignment. Details in Garage. I hack it up, Ted tunes it in.