Things you need to take into consideration.
Electrical system. It takes power to make power. If your car has a 80 amp alternator and you don't plan on changing it.. 600 watts from a very inefficient slash amp may not be good for you.
Those amps pull a lot of power to do what they do.
If you listen to bass heavy music all the time you won't want to max out their ratings.
If you are into sound quality, that's what those subs do well, you will listen to mostly 80s music and Jazz. In that case it don't matter because you won't use much power daily.