Afr vs combustion efficiency...

[bme30]

A quick rundown..
Gsxr 750 itb
S52 21.5# injectors
Tunerpro with ostrich 2.0 with software from bmwconnect
Aem wideband afr

Ive been running this set up for a couple months and did some minor dyno tuning.  Had the afr around 12.5 wot

Since the air here has gotten cooler the dense air leaned out my afr to around 13.5.  And what a diff in power!  

Now here's the thing.. All motors are different.. Some produce more power rich and some a little leaner.

Ive always heard that our m42 ran lean from factory.. Does anyone know or have a factory afr reading wot
Second to that anyone running an afr wideband on their chipped ecu.

Id like to conpare and see the general afr differences.

Thanks

Here is the set up