Stay with me here
I had my Attitude in the manifold and Autometer post-turbo. On a good pull up a hill they would be about 75*F apart. If I flipped their positions I would see 300-400 difference, sometimes 500*F. The Autometer read hot or the Attitude cold or a little of both. I never did figure out which. I sold my juice (don't ask why... I'm an idiot) so now I drive according to the Autometer in the manifold.
Long story short, good luck. Pick one and run with it. I'm probably going to get a new EGT gauge 'cause I really don't trust the Autometer I've got. It's the only way to find out.