i'm gettin about 10 mpg too but in stop and go traffic with the A/C off and the SES light blinding me, it says that the rear O2's are bad....but that might be because of the gutted cats...iunno (lol) so the front 2 sensors are the reason why the miliage is shitty?

 

If you have a light, you will not know when other codes come up. you may have several codes stored in the computer now.

 

i have the 02's code and then i had the low voltage when i did the !EGR/AIR mod and that my cats where bad. i once had 9 codes at the same time but took care of most of them sept these 3, would running the 02 sims in the back take care of all 3? but my mileage would still be shitty right?