I guess this means restrictor plates. Welcome to Least Common Denominator racing.
'Following suggestions that there is a differential between the performance of engines used in Formula One, the World Motor Sport Council (WMSC) has decided that should this be the case, and should the teams wish to eliminate this performance differential, they may be allowed to do so by reducing the performance of the more powerful engines. However, no engine upgrades will be allowed.'
Those of you who are inclined toward conspiracy theories (like me!) might draw a connection here between this new rule and Max's failed plan to have unlimited rev Cosworths, which would have made any new team - like, I don't know, Manor - instantly competitive. (Yes, WB, I'm sticking to my guns!)