Caps are not totaly worthless. Just need the corect size for your system a 2 farad cap for the sub is good. also an Optima patter is a good upgrade My old system ran 2 batterys and caps on all subs. Never a problem.
Yes, H/O alternators are available for the Aveo.-Drop me a PM. I would first suggest upgrading your battery and the big 3.
Definition: the "Big Three" upgrade means improving the current capacity of three cables: 1) alternator positive to battery positive, 2) battery negative to chassis, and 3) engine ground to chassis
Remember:
The alternator makes the power, every additional battery or cap put stress on the alt thus the reason people upgrade the alt first.
The battery will kick in to provide the missing amperage.
But batteries take time to charge/discharge unless you have a BATCAP, Kinetik, or XS power battery.
Capacitors are not worthless but for the cost of one that would be effective for your system a battery would be cheaper and provide a better reserve of power.
Powerful amplifiers are cheap, the electrical to run them effectively is not.
Recommendations:
BIG 3 upgrade with 1/0 gauge wire
BATCAP 2000 (upfront)- provides over 1000CCA
or
Kinetik HC2000 Power Cell (upfront) - Ah: 102, 2000Watts
or
XS Power D5100 (upfront) - MAX Amps – 3100