hey everyone. its my first post here, but definitely not my last. but anyway. im going to get a new system in my room. im gonna need a sub. i want a 50 dollar sub. what im lookin at is the alpine type e, mtx 4500, mtx 4000, RF punch 1 and the JBL GT100. which one of these is the loudest, and which do you think has the best reliability. also, does sq mean sound quality? ive just been wondering that. thanks! really what this is about, is whether or not the 4500 and the 4000 have a big difference in spl and sq. im really leaning toward the 4000 cause of the price, but god! the 4500 just looks so beautiful!