Tuning for headers

[BLG355]

I have been reading for the last few days about changing the tune for headers and/or if you move the O2 sensor. I installed a set of Hedman shorty headers with their larger Y-Pipe. The o2 sensor is in the y-pipe, after the two pipes join together, which is where it was from factory. I am getting a very slight surge while cruising that I am trying to eliminate, I would like to leave the O2 alone if I can. I have found very little on the topic, but it seems that everything points to Integrator Delay vs Airflow. I tried using the stock settings and the ones in Marks tune, and I've even added to both trying to get a sweet spot but just can't seem to get it to stop. Has anyone had similar issues? I attached a log I just ran and a snip from tuner pro. It was way worse with other injectors I was running, I thought I got it all out when I swapped injectors but I can still feel it. Any help or suggestions is greatly appreciated. Specs are at the bottom.

BLG

[lionelhutz]

Some of those other filter coefficients might come into play, like the slow O2 filter coefficient or the integrator delay.

I've had to play with the O2 voltage thresholds before to help with a slight surge. Basically, increase the low end slightly.

[murr32]

I've just gone through a very similar issue with a slight surge at steady state cruise. WB showed wide fluctuations in AFR. Lowering PRP - Gain vs error and PRP - Gain vs airflow by 25% removed the SOTP surge and reducing by an additional 25% (50% of stock values) give a steady state cruise AFR or 14.6 - 14.8.

This was on a non-stock, non-GM engine but I have read in other posts that this is sometimes required for non-stock cams, etc.