Is the engine software or the exhaust system different to other state´s? Or what?

 

Okay, since everyone has been asking this question I came up with some data if you want to wade through it.
http://www.epa.gov/otaq/cert/veh-cer...sults_full.zip
It appears as though the 50 state configuration for the Mustang has emissions low enough to pass California emissions.
Please correct me if I am wrong...
I believe there is no actual difference at all.

 

AFAIK all cars sold in the U.S. now meet California emissions. The sticker is just kinda a carry over from when California had much more strict emissions regulations than other states. You get charged a "smog" fee/penalty if you try to register a vehicle in California origionally from another state that does NOT have that "california emissions" sticker.

I once got a great deal on a car origionally bought in Oklahoma from a roomate because he feared there would be a huge penalty, as luck would have it, it had the sticker and I wasn't charged.