Steering Box Ratio

66fs said
195/55R15, V rated, 200 tread wear, 35 psi. I may try a 20:1 box myself.

I think mrgtx has 225 or 235 wide front tires.

Early A-bodies weigh less than later ones. Earliest is lightest, latest is heaviest (in general)

35 psi helps too. The sticker on my 2015 Challenger says 32 psi.

And mrgtx is running +5 deg caster vs 2-2.5 caster.

All those things add up and will give quite a different effect.