So my v6 engine has to come apart and I'm considering port and polishing the heads, I've seen a multiple number of people say they have to retune your ecm, if I still have an oz sensor will I have to manually retune or will it correct itself?

 

Porting alone will not change things enough to require a retune. Might need an adjustable regulator to optimize the WOT fueling though. GMs are typically pretty rich at WOT as is so it may actually make more power from the added airflow leaning it out a bit. Assuming we are talking about a stock 2.8L or 3.1L porting will gain next to nothing. I rode in a coworkers 3.4 Firebird back in the day that had the whole upper end ported. It felt like any other V6 F-car to me.

 

Putting 3.4L heads on the 2.8L/3.1L take make a "hybrid" is a popular upgrade in V6-60 circles, or was back in the day. The 3.4L head flows a lot better, if that's what you are after. But that would require I tune I think.