I have heard of people having problems, the guy I bought my s4 from said he tried to save a few bucks registering his pacifica at like a 10K difference. He said they caught on and made him come back and pay the difference. I dunno you can always just say it was a mess but driveable. I think anything over 10 years old can be registered for less than a grand.
I got away with murder when I registered both my cars.