Hello BadDog,
For your information, a "hack" is considered anything that changes gameplay by the term itself. Cleo modifications, aside some that are only visual modifications, are actually considered "hacking" and it is against the SA-MP Terms of Service to use them. Also in regard to your question, everyone in the YouTube videos, that are using it in SA-MP, are considered hacking for modifying gameplay. However its possible in singleplayer, so that is not "hacking". I know its not nice that we cannot use taxi boosting in SA-MP right now, and I will hope to see it in the future.
Regards,
admin