Don't worry, you won't go to prison if you remap your car. But the procedure to get all the paperwork done is ridiculously expensive, so you better buy a more powerful car in the first place.
When I called my Insurance Co Zurich about a quote for a re-map, they would not insure me and also want to charge me £40 more per year for rear LEDs! They are still pretty cheap though!
But got some excellent quotes from Admiral and Elephant through comparethemarket.com.
However, the re-map would cause major problems with VW warranty and servicing if they had any inkling that this had taken place.
So I am being 'jailed' from a re-map!