I'd go with a single 12"would that kicker power 9500 10?. i am thinking one 12 between buckets or 2 10's. in the el camino.
idk man theres alot of options out there.. each person might like a dif. sound .. As far as getting loud goes , for a daily driver to me anything over 140 is good , 1ve hit near 145 off music with a single 12w7 which is nowhere near an spl sub but i built a box that worked w my car and the power i had .. good luck manya'll been super helpful thanks.