The amp puts out 300wattsx2, and yea those are speakers off of my radio in the house i had those before i got the subs and was to tired to take them off, but I'm def. going to take them out when I install the next subs... and maybe buy 2 6X9 with a small amp just to level out the sound... I'm sure the bass is going to be crazy with 4 more subs... I'm going to build a custom fit box to go around the one i have now to fit the new subs so it'll take a little time before i get them installed but when its done its going to be awesome...