Because I have been out of the Mustang seen for the last few years, excuse my stupidity. But I do have some questions regarding the 05 and up models. I have been told that with pretty much every mod, that the computer would have to be recalibrated. Is this true? If so, what mods can you get away with that will not affect the computer? I have an '05 GT that I just bought, and I plan on changing the exhaust very soon because it's too quiet. I plan on running an off road x-pipe, like I had on my previous cars. On those I had to put the MIL eliminator to stop the "check engine" light from coming on. Will I run into similar problems when I remove the stock converters?