Im currently not running a cat. Straight 3inch w/ a lot of backfire(Getting Tuned Soon to Compensate).
Yes you will have a boost increase, and a good chance in power increase, and possibly check engine lights.
Also as for the fuel economy, sure maybe... If you can keep your foot off the gas pedal.
LOL at that CEL Fix Adapter price... You can get one at NAPA for 8 bucks.
