I have read posts that says if you change your muffler, you should also unplug the battery for 2-3 hours to allow the CPU to readjust. Is this really true and necessary? Or will the computer adjust over time?

 

If you feel that car goes very different (slower) after install than it was before - yes, unplug it for 3 hours so ECU would reset.
I do not think mufflers replacement will cause such effect as mufflers aren`t that restrictive to begin with. Most folks myself included had this effect after upgrading to sport cats.

 

+1. Just changing mufflers shouldn't need an ECU 'reboot'. With more extensive mods, it allows the ECU to adapt a lot more quickly to the new engine characteristics.

That said, why not try a battery disconnect for a couple of hours? No apparent downsides and sometimes it really wakes the car up. Just remember not to shut the front cover as it's electrically operated and a pain to get open without electricity! You'll also get a couple of warning lights nagging you when you first fire the car up after the disconnect, but these will disappear after a few yards driving.

 

The only thing a different muffler will do is enhance airflow ( most likely only in the last 1000 rpm). Since the airlow is being continuously monitored, the air/fuel system will adjust automatically.

 

Thanks guys for your response.