NHRA doesn't adjust the indexes in most S and SS classes. They will add HP and the HCat will go to FS/C then B, then A. The same as happened to the 5.7 Dragpak. It is up several classes. At 600hp and 7.5 lb/hp that's a heavy car at 4500 plus 170 for driver if I read everything right.
Strange thing to me is NHRA has the HCat listed for the 2015 Chally too. Maybe the 2016 too, I didn't check that year.