707 Hell Cat, what does it mean?

I think the OP was about what it MEANS to the 60-70 “muscle cars’ ” value.
Immediately, I THINK it won’t hurt.

it will put more people into new challengers. i see tons of people on various mopar sites selling their old cars now and buying new challengers in the mopar world. the hellcat may get even more people into the dealership to check it out. sure they all won't buy a hellcat but maybe while in there they really like a more affordable r/t or srt.

Is there something else exceptional about the car besides mods to the engine?

i believe the 2015 challenger has all new updated suspension. i'm sure with 700hp that they also upgraded quite a bit of stuff to handle it.