people will always do as they please, but just a recommendation from someone who has been there and done that a long time ago.. spend that money on electrical FIRST. Alt's, wiring, and batts alone could set you back $1,000+ .. it was very disappointing to have a system that could slam, but just didnt have the power to get there!
Anyways, my recommendation aside, if you intend to get your subs and amp first trust Mylows.. great guy, very helpful, and he has had his hands on a little but of everything so his advise as far as setups are concerned is golden.