Kicker Solo-Baric S12L7 12" Car Subwoofer

I had 3 of these subs in my 88 CRX and it sounded pretty good but I wanted to enter compitetions. When I realized these subs just where cutting it was when my brother came over the show me his new system. He had the exact same amp as me but had just 1 15" cerwin vega stroker that blew my kickers away. I also had a power capacitor and 2 car batteries so I assumed my amp was messed up. My bro took out his 15" stroker and we put it in my car and bang! My car sound 2 times better than his did 5 minutes ago. The power capacitor really made a difference but that also made me realize that my kicker got to go.