That might be slightly true in a V8 or V12 engine that's been run at max rpm on a race track. But driving a little four cyclinder Toyota around? There's no way that's going to be an issue.
I don’t think Prius and other Toyotas in the US have them as far as I know. In any case, it is illegal to tamper with any kind of emissions systems, not to mention that the car will fail the emissions inspection or test.
This is a Europe/USA difference I'd missed. The GPF gets half a page in the European manual about the possible error conditions - posted here for the benefit of others.
Paint flames on your car, it will go faster. If you put bigger tires on the back you will always drive downhill and save gas.