So I've been a long time VAG owner (1.8T), and all my tuning knowledge is acquired from here, and most of the AFRs are in the 13s when rich. I think the richest AFRs are 12s (especially Stage 1) here. However, I recently checked out Subaru ROMs (even recommended stage 1 AFRs), and even factory tunes are as rich as 8.8:1. I've attached stock fueling for an 01 Impreza STI. Why do they have to run so rich, or how are we able to run so lean?

our cars are on avrage are a whole point or more lower compression, we have forged pistons and our kr is night and day better then that denzo junk

Not just that though, manifold/port/piston/cylinder design, spark energy/efficiency/placement, tumble effect/atomisation, material structure and resilience, fuel/reactant and, most importantly - evolution of the control systems, all have a say on where proper deflagration comes - hence why people say log! 

https://en.wikipedia.org/wiki/Deflagration

https://en.wikipedia.org/wiki/Thermodynamics

https://en.wikipedia.org/wiki/Analytical_dynamics

https://en.wikipedia.org/wiki/Law_of_mass_action