mustang owners help
I'm thinking about changing the exhaust on my 02 gt, I'm planning on an offroad x pipe and slp cat back, a friend of mine has the same exhaust on his 01 bullitt and it sounds great, the only question I have is how much will it hurt the gas mileage, his dropped tremendously but he did nothing with the o2 sensors, I was just curious if that caused the huge drop in gas milage or is it just common when you go to an offroad x and high flowing exhaust. This car is my daily driver for now so I don't wanna hurt the gas mileage too much. Thanks for the help

Is he using using mil eliminators?

no, I think that is why his gs mileage is soo bad, I don't know anything about fuel injected cars, my camaro I have, I have an old carbed 355 in it, I know alot about carbed cars but nothing about fuel injected cars. so in this mustang build Imma need alot of help from some of the mustang owners on here.

The CPU can tell there is no cats and is trying to adjust the air fuel ratio to compensate for it, a less restricting exhaust should save gas if tuned correctly.

Sounds like this problem is solved. A good exhaust system with the MIL eliminators or a chip/tuner with a setting for turning off the second O2 sensors will give you IMPROVED fuel mileage.