Well, it doesn't void the entire warranty, just any damage that can be attributed to the modification. Probably the simplest example would be the broken flanges on catalytic converters that a number of members with non-flex pipe aftermarket exhausts have experienced. I doubt you'd find a dealer that would cover that unless it occurred with your stock muffler. Having said that, it sure hasn't stopped me or many others from having fun modifying the heck out of our smarts.
PS Welcome to the forum and congrats on your new smart!
I think it depends on the dealer and what side of the bed he got out of that day. they must show a direct link or you must prove the mod did not cause the issue.
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