I want better mpg. Is my cai and unbolted cat-back eating more gas or eating less because the engine is more efficient?

Also I want to get a new fuel filter and do that acetone stuff and see if that helps. The car is in good shape and runs fine. I also will get an oil change as well.

But should I bolt my catback up and remove my cold air intake?

 

I would say to keep the cold air intake but I'd bolt up the cat back. I did a bunch of chassis dyno's at my school and when we would remove exaust we would gain upper rpm hp but it would kill the low end torque. If your looking for gas mileage your best bet would be the torque at part throttle driving. The cold air intakes help all the way around due to a denser air charge.

 

Read for every 10 degrees drop in air temperature you gain 1% in horsepower as a rule of thumb.

 

My husband says they will decrease your mpg.

 

a catback and intake will certianly help your mpg but only if you accelerate at the same rate as before. If you get this stuff and go flooring it all the time, you wont notice an increase really