Hey i just turned 16 and have been saving up for my system for a few months now and finaly got it. I just got a MTX 15" 9500 and want to build a box for it. I have a 2001 tahoe LT and the third row seat is out. I want to build a box that is ported and takes up the full width of the trunk. My question is, tuning.... How do i tune my box to the specs and have it the length i want it?