No worries, here to help.
Do you access to a termlab spl meter?
I say this because its invaluable to test little things that may or may not increase your score. For example i open my glovebox and i gain 0.3db, i know its not much but if you can find 3 or even 4 of these little things then theres atleast a db right there. Things like glovebox, front seat all the forward and tilted all the way forward, sunvisors up or down, back seat up or down and vents open or shut on the dash all are worth a try.
Heres a link from a good friend of mine who was kind enough to write up a tutorial on SPL competitions, worth it to take some notes.....he knows what hes talking about and has tought me 80% of what i know about SPL.
Technical - Beginners Guide to SPL, Competing & Testing - Mobile Electronics Australia
And_ROOS - Yeah i know what you mean....a proper enclosure can make ALL the difference to how much bass output you get. That box i designed is SPL orientated, but if you were to make the port say 35 x 10cm and about the same depth it should play nice and low, which means it'll play most music.