For competition, yes. The other day was just testing though. It's nice to know that no matter how badly I treat it (track or road), it still won't be injuring my passengers.

That said, in a 720kg car with another 70kg of driver, an extra 1kg of Empeg won't make a lot of difference to laptimes. I probably lose that much weight in fuel each run, and I don't go to the bother of running with a nearly empty tank and filling up between runs. At the sort of club competition level I'm entering, the driver makes by far and away the biggest difference.