Hello, I am getting a 2k6 Silverado ext cab. Would like to put a decent sound system in , but I don't want to ruin the capability of seating 6 ppl since my family is going to consist of 6 ppl soon... I know they make an under seat box, and I like that idea. Has anyone had one of these boxes in a ext cab truck and how does one sound. or is there a better way to utilize the space underneath the rear seats?