DECA Autosound in Verona,MS recently did an excellent job installing my first system. I first got them to build me a custom ported box for my 15" L7 to fit right behind my seats in my '95 Blazer. I do not know the exact specs on the box, but it gets LOUD! I then got them to go ahead and wire my vehicle with 4 gauge Rockford Fosgate wiring. They did an excellent job. I just have a 1000-watt Kenwood X811D amp pushing the L7, and it is definitely one of the loudest systems around. I believe a lot of this is due to the box they made for me..
I will definitely go to DECA for all my installation/custom box needs!