Regardless of the subs you are using, an improper system setup will damage your equipment, there are 3 basic subsystems to be checked for safe operation, proper electrical including power wiring to the amps, proper enclosure and correct gains setting procedure for the amps (decent quality signal wiring as well of course).
keep in mind that just because a sub can "take" 600 or 1000 watts, that doesn't mean it needs that much power to reach X-mech, or X-max (full mechanical excursion) The amount of power needed to reach the full output of the sub depends on the vehicle, and the enclosure.
I have assumed that X-max is the maximum clippel-verified linear excursion and that X-mech is the absolute excursion limit, however non-linear it may be.