Well that's really no f'n help at all.
he's telling you all the right things to do... You have everything set up horribly to be honest. Sundowns arent meant to be in put sealed boxes and ran on dirty power like audiopipe. Not to mention your voltages are pretty bad from weak stock electricals so not many amps will make rated power inside your car. Capacitors(excluding ultra-capacitors) are complete garbage, sell that off to some other noob on craigslist. Does more harm then good.
Your assuming the subs are bad bad and want to get something that will destroy your car but you dont realize getting loud and sounding good is from the enclosure, power, and power supply. AKA custom enclosure, better amp, big 3 and AGM battery under the hood(maybe in the trunk too) need around 55 amp hours for every 1000 rms your running. If your stock alt is 80 amps and under, you might want to get a rebuilt alternator above 120-130 amps if your on a budget. If not then grab a high output alternator, but only if you see your voltages dipping very low under 12.8V with all the extra batteries and big 3 upgrade done.
Nasty08impala sounds mean but he means well, advice is solid. I mean you can always get a pair of JLs or kickers that work well in sealed boxes... Then a guy with sundown set up correctly pulls up and melts your face with bass.
If you need a box , nutdawg or boomsday can build you a box for materials + shipping costs excluding labor costs which is a killer deal compared to audio shop prices.
Try to save up for a soundqubed 2200.1D for a quality amp. If your on a budget, sell that audiopipe for a PPI Black Ice 1800.1D, will do rated a lot cleaner and more efficient then audiopoop.