Was tired of spending half my day in the transit and not having a good sound system. Since its a company vehicle, I dont want to/cant change the head unit, so I used a line converter, and added a 13 inch power acoustik slim mount subwoofer in a sealed box to the stock radio. I powered it with a 400 wat amp under my seat( sub is able to hold 700 watts). Since I have the bulkhead right behind my seat seperating the cargo area from the from cab area, it had to be a slim line sub. The box the sub is in is only like 6.5 inches wide at the base and 3.5 at the top. It fits pretty good, and allows still some leg room in the passenger seat area, should some one have to ride with me. I have some system tweaking to do, but it sounds really good so far. I'm really impressed with the sound now. I'm sure with a bigger amp t will rattle the truck no problem but with the amp I have, it does quite well to fill the interior with mirror shaking bass. I am still considering upgrading the stock 5.25 inch door speakers with something better, but am going to hold off for now.