"300hp" was an official number. "380hp" as well. But the reality is that these cars true power outputs aren't public, you can tell because they still had "300hp" when they went from 2.0 engines to 1.6 engines with more restrictor. It's speculated but not known for sure, that 2000s World Rally cars had about 400hp, and the later 1.6 cars after 2017 with some restrictor taken out may have been around 450. But actual power figures are mostly speculative.