Thought I would give a little input on the stock tune after I installed my AEM wideband this past weekend. FYI I welded it in about 8 inches after the turbo before any cat's In the stock DP. The Rom Raider logger parameters still aren't ready so I don't have the ability to log knock, so I have been reluctant to make any significant changes.
I knew the stock tune had a major lean spot down in the lower RPM range from looking at some of the dyno plots of similar 2015 STI's, but WOW I didn't know it was this bad. Yesterday I rolled into full throttle in 3rd gear and about 2k RPM. It does its usual bog sound and barely accelerates, and as boost started to rise I watched the AFR's as they CLIMBED to 13.8:1 at about 15PSI boost. Once I hit that boost level and saw AFR's that lean I immediately let off. The entire event was probably only 2 seconds.
Today I did a similar test this time from 2.5k RPM. It went lean again, but this time not as bad, and when it finally dumped fuel, AFR was 10.2:1.

Ridiculous. Who tunes these things from the factory? Its almost as bad as the stock head unit software.
I just thought I would share this info since there probably aren't many people out there monitoring AFR on a completely stock 2016 STI yet. I just can't believe the stock tune is this dangerously lean. From what I have heard, the Ignition timing is also extremely aggressive on the top end. I only have 91 octane here in California, and my IAM was surprisingly .875 IIRC, I thought it would be less since the timing is pretty aggressive (I have not logged total timing, nor have I studied the timing tables enough to get a good idea of total timing).
Td-d, a quick note: the MAF Compensation (IAT) table in both Rom Raider and EcuFlash both don't look right. Could you take a look when you get a chance. I am also eager to log data once the RR logger parameters are defined.
Thanks to all who contribute to this great forum!
Jerry