You have 2 of these subs so you need 2000w of power to get them running at there full at least.
Is this for daily listening? Or you competing with it?
Just woulda thought you had a better idea of what to get if you were competing and if you bought these as daily listening subs there not really meant for anything but to go loud. they wont give great soundquality but people will hear you....a mile away with 2000w of rms going through them.
Your also gonna need a good wiring kit which will be another £100-£200 on its own.