kicker l5 help.........?

[Ben]

alright, i have a single kicker l5 15" in a ported box, a hifonics brutus 1200watt, 2farad cap, and extra battery all using 4gauge wire. the box is like 3 cubic feet . now, i have a program on my iphone that lets me play different frequencies and this sub sounds like pure **** with anything below 40hz, anything above 40hz is pretty effin loud. i'm not sure what the port is tuned to but i'd say its around 45-50hz. it hits the hardest on about 45hz-50hz when played. now i figured this setup would sound a bit louder than what it is, but i'm thinking maybe its just the box. if i had a bigger box, (about 4.5cubic feet) and tuned it to about 30-35hz would it hit harder? ALL i listen to on this sub is rap, and hiphop. so, i have to listen to certain songs because of the other ones being too low for it. like da blow by lil jon, hits the hardest on this sub..stuff like dime a dozen by too short, doesn't sound loud at all..i mean if i had a bigger box, and tuned to about 30-35 hz would this sub play louder, or do i just need another one and a bigger amp? thanks