Very illegal in all Western countries, but there are (expensive) navigable loopholes for vintage and reproduction-vintage. Or you can replace your ECU with a Speeduino and bet on never getting checked (pretty safe bet I'd say). If Speeduino supported Hybrids I would've done so already :D

GitHub

GitHub - speeduino/speeduino: Speeduino - Arduino based engine management

Speeduino - Arduino based engine management. Contribute to speeduino/speeduino development by creating an account on GitHub.