Your findings are what I usually hear and see on top mount setups. If you were to pulley it for 12 psi id bet you would see 160 degrees too.
2011 SS IOM Vert. ECS Vortech 14 psi, Water/Meth, Wideband with Firewire to SCT, 2800 stall, LT headers, Drag radials, Drag alignment, Cradle Bushings. Details in Garage. I hack it up, Ted tunes it in.