Alpine stuff.. help plz

hey guys.. i got an alpine type R awhile ago.. and for some reason it sounds like crap.. i thought it sounded ok.. until i sat in a few of my friends cars..

1 JL12w6 sealed
1 Kicker CVR ported
2 Kicker CVR ported
2 DHD (wtf?) sealed

ok... for some reason my bass.. just sucks crap compared to all of theirs (they all buy prefabs) the bass is REALLY MUDDY i duno whats going on.. im using a 1.25 cu.ft. box.. but after the sub is in there its prolly 1.1 or something.. does .1 cu.ft. matter that much?

as for the amp.. (mrd-m301) i have the input set on -6 db, and the gain set on +6db am i doing something wrong?

last i have it low passed at 80hz 12db slope.. i just dont get it.. i've heard type R's before and they sounded really clean and tight.. but mines sounds loose muddy n boomy.. WHY? if anyone can help... please
and for the amp.. how do u correctly set the gains on an alpine amp? (i have a mrd-m301) i've been messing with it for awhile.. but the bass seems kinda muddy now, not clear at all.. anyone help? also its not a knob to adjust the gains, it has gain, and input.. the input is from -18db,-12db,-6db,-0db and the gain is.. +0db, +6db,+9db can anyone help? there are alot of other options but i didnt use any of those yet

it sounds like the input is the traditional "gain" and the gain is a bass boost, but I can't tell. Try reading the manual, it may explain it better. If you check it all and the settings still seem right but the bass sounds muddy, you may just need to turn down the sub and get a better front stage

subbass, by nature, is muddy. It's the midbass and even the treble to a degree that give it any "sharpness" or definition. Time correction can help too, if you haven't played with that yet