After the qualifying results, something clearly needed to be done in the name of class parity.
DSC is reporting that the Fords will have a reduction in boost from ~4000-7000 rpm, (in addition to the weight penalty), whereas the Ferraris are slowed solely via added ballast. Aston Martin, Corvette and Porsche all get extra fuel capacity, too, although there's no restrictor adjustment for the 911s.
As for testing, the
preseason test that determined this year's initial BoP was already done by independent FIA test drivers. The situation in GTE is unique given the extent of manufacturer development, compared to GT3 once the cars are in the hands of customers.