Here is a second hand story.
I just bought my 535 in Pennsylvania and brought it back to CA which has the strictist emmision standards in the country. My boss who thought I was totally nuts for doing this kept telling me this story to try to talk me out of buying my car. HIs former partner brought a mercedes in from europe in the early 90s and had to spend $3-4 (probably equivalent of $6-8k now) to get it where it would pass smog test and could get registered here.
If you are going to do this consider the state standards in addition to the national ones. Not trying to talk you out of this either. I love people who are bonded with their cars. Just another something to consider.
Dinan chip, Bilstein sports w H&R, RD sways, RD strut brace, 750 bushings, Zimmermans/MetalMasters, O.E. M Pars, Eisenmann muffler