you always want to have a bit more amp power than sub power. when you really crank it up with an underpowered amp, it begins to "clip" where it sends massive distortion in the form of extremely high amp waves. this causes the subs (or speakers) to blow in short order, while slightly exceeding a subs rms power with a larger amp is far less damaging. i think you overestimate exactly how much bass you really want. if you want any semblance of sound quality, you can only have so much bass before its not music anymore, its just bass. i have 2 fosgate he2's, and i have to keep them turned down so it doesnt drown out the rest of the music. if your talking about pushing the kinda power your looking at, you are going to need not only to upgrade your deck and interior speakers, but your gonna need (amongst other things)- lots of dynamat or other sound dampner for at least the trunk, probably the doors too, a custom box, heavy gauge wiring, a deep cycle battery, a more powerful alternator, at least 1 or 2 farad capacitators, etc. that stuff adds up real fast, im guessing at least a grand or two (depending on how much the custom box is, most pre built boxes cant handle a sub that large, and how much the rest of the installation is if you dont do it yourself) just for the accessories, not the actual audio equipment. add that in, and your talkin 3-4 grand when all is said and done.