I think I have decided on a sub, and this is the one. Just a few questions that I have about it. What is "better", or it doesn't matter it just depends on what amp you have, D2 or D4? I have no amp..so that is why I am wondering. I think I want a sealed enclosure since this will be in the extended cab of a truck..but what size do you think? And just what do you think about the sub overall? Thanks alot.