I finally had the exhaust done on my 2008 1500 Hemi - I went with a Gibson single outlet right behind the pass. rear tire (exactly where the stock tailpipe was) - and I love it! In the directions from Gibson it says to disconnect the the negative battery cable so that the computer will recognize the new exhaust.... is this really necessary?? I've never heard of such a thing. I did not do this and the truck seems to be running fine.

 

It can't hurt. That might help the computer get used to a less restrictive exhaust faster.

 

It should work itself out within 500 miles. The computer learns and stores all the parameters includng readings from all the senors and even your driving style. The computer is constantly updating any changes, but does more on a rolling average. By resetting or disconnecting the battery, the settings are defaulted to the factory settings and the common thought is that it learns the new parameters quicker. Many do the reset after a tune up since the quality of the spark and so on may be different.

 

I agree. Can also reset the PCM by removing fuse #31 and turning the key to run, leave it for 20 seconds, turn off ignition and replace the fuse. Removing the battery cable can take as long as 30 minutes to clear the cached data.