You probably won't screw up anything. I don't think the vtec engages based on the SPEED but the RPM. I can engage the vtec just reving the engine out of gear. The gear he is talking about is is not part of the engine or tranny, its a gear that basically winds the speedo around the dial.

You can grind it down do whatever you want, problem is the officer may ask why you didnt mention the improper speedo when he pulled you over, and a slew of other things. I would suggest a lawyer help you out.