I have 2 RF P3 subs and a hifonics 1200w amp. When the amp is wired to 2 ohms it has 900w and wired to 4 ohms it has 450w. The subs are 400w rms each. But i have gone to two places to have it installed and one said he would wire it to 4 ohms and it will be underpowered and then best buy said...