Precat effect on Primary O2 sensor?

[quick72toy]

I just found that my precat suffered a meltdown at some point in its life, and is basically gutted. I was wondering how much effect it has on the 1st O2 sensor.
Has anybody measured the AFR using a good precat vs a gutted precat, or header? Do you think the gutted cat would cause the O2 sensor to read slightly richer?

BTW I'm not concerned about the CEL and 2nd sensor for now.

 

[NCZ13]

well its not the first o2 sensor that would be effected, it would be the post cat sensor.

i have a wideband, and my car runs fine in closed loop. In open loop (WOT) the AFR are not where they should be, but thats attributed to the bolt ons i have, and the lack of tuning. my stock ecu is at its limits fuel wise.

 

[quick72toy]

Thanks
I just realized that the O2 sensor plugs into the manifold above the precat.(braindead I was thinking it plugged into the side of the cat. I should know this I just had everything off. (braindead