A 160 HP reduction and a corresponding drop in fuel cost is one way to do that.
I still think people will complain about P4 vs Jackson match up because the ROF, accuracy and mobility is untouched. From what I remember, Jackson HP buff was due to large game mode players being super frustrated with glass cannon of late game USF and the inability to chase down Panthers or plan grand offensive vs elephants. I am talking about strictly from 3 v 3 and 4 v 4 perspectives and playing USF feels a bit more competitive in these game modes.
Keep in mind more people play 3 v 3 and 4 v 4s and P4 vs Jackson match up is not really a problem.