The FBI has a special branch with the sole mission of identifying criminals who have changed their transmitter crystal. They hit your shop in the middle of the night with a SWAT team and seize the offending transmitter. Then they haul you off to an undisclosed location and interrogate you for hours and show you satellite images (obtained from the CIA) of you actually operating the illegal device in order to coerce a confession. You're toast! Better hope they didn't find those pillows you tore the tag off in violation of Federal law! That's another whole can of worms.