I just got tuned @ a very reputable shop here in Ontario Canada.
Put down 613/546whp @ 17psi

He tuned it in 5th gear.
AFR in 3-4th gear are 11.9-12.4 at WOT.
It is cold here. 50F
Haltech Pro Plugin (Full Standalone)

1000cc injectors
485walbro pump
Momentum ST kit.
full FRS

Wondering if its just the cold dense air?

He usually works on GT-R R35's, EVO's and STI's.
Do they usually have this high of a AFR while WOT?

He said that when he tuned it, it was Low 12's @ tailpipe, but now its reading it off the 02 sensor @ downpipe.

 

Hal @ Dynosty straighted me out with a 2 hour e tune.

It was Air temp correction problem.

and now I got boost by gear