What are the disadvantages of fiberglass boxes in SPL type builds? The reason I ask is I am just getting sick of the HUGE box in the back of my truck looking ugly and all, and I am thinking of doing a really cool looking fiberglass box in the back and using Aero ports for ports, as I have 4 4"ers ready to go. I may also go to two 15's as with the fiberglass I can get into all the little areas that give up air space and fit a much larger volume box in there using up less space. Let me know what you guys think as I value your opinions...you all do this more than I do...THANKS! I am looking to increase my SPL over the existing box and hope this will work.