I recently got a new Magnaflow cat-back and CarSound high-flow cat installed.

Should I have reseted the ECU? I have been driving for a couple days and have a feeling my MPG has decreased (I havn't been rough on the car btw..)

 

it's not really necessary, but if you want to, it won't hurt

 

allright thanks..i did anyways just to be safe

 

And did you see any improvement?

 

i put a new exhaust a year ago and never reseted my ecu how do u do it and why does it need to be done i got better mpg and more hp and nothing wrong why would you need to reset ecu

 

i already said you don't have to do it.
i just told him to do it if it would make him feel better about it, because it won't hurt anything.

 

You just might want to reset the ECU so it gets used to increased air flow so it can increase fuel needs if needed. Its not necessary but if you want to just to be safe

All you have to do is un attach your neg batt. terminal let it sit for like 5 min then re-attach

 

But then you have to leave the car on for a while so it can relearn everything

 

I do not think that an ECU reset is really necessary in this case. It will take more than a couple of days of driving to reliably know whether there is any effect on gas mileage.

 

Reset your ecu and then turn your car on and DO NOT touch the throttle. let it run for like 5-7 min. unplugging your battery resets your ecu and letting it idle for a while alows your car to reset its fuel to air ratio... you prolly wont see, feel, or notice any difference in any way but if your gonna do it thats how its done. just be ready to reset all your radio settings :P