Pre-cat O2 Change
 

So I just changed the pre-cat O2 yesterday and I noticed a bump in power after 5 mins of driving. I'm not sure if this O2 was factory but I've never changed it in the 3 years (about 30K miles) that I have owned it. The car had 102K (165k km) when I bought it and it now has 132K (213k km).

I noticed I was getting around 21-24 MPG so I'm hoping to see an increase from that.