A perfect Black Market will araise: altering or deactivating the software in the black box. They’ll probably outsource the work to India which means 65% of the time they’ll be faulty anyway.
I know some guys who are really, really good at re-programming ECUs (engine control units) for performance. It is sort of an open source project among a small group, if you will.
I have little doubt they could take on such a project. One of the leaders of this crew is anti-Big Government enough that he would probably just release the code, no black market needed.
But no worse than the originals cause that's what the OEMs did too....