I have never had any fi subs before. I had some jl audio subs. I am trying to build a system for my truck. I will try to be as detailed as I can for what I'm looking for. I have a 2006 Trailblazer SS and right now my sound setup is the stock bose system. I still have the factory 6 disc head unit. I'm very interested in the 15" BTL subs. From what I've been reading from the posts on here I may be good with just one 15" sub. I have always been used to having two subs. I want to be able to have a wide range of levels as far as sound. I mostly listen to rap, rock, and r&b. I want the sub or subs to be capable of hitting extremly deep levels. I wouldn't even mind trying to enter into a competition if they hit low enough. I need to know from everyones experience would you reccomend 2 15" subs or is one enough with the right box? What amp should I use? I'm hoping not to spend any more than $500 on the amp if possible. Do I NEED a alternator and a aftermarket HU? Do I need a battery as well? I know I am probably asking for any expensive setup. But I am trying to go the safest route for my pockets and get the best bang for my bucks. From what I've read on different posts I know you guys have a lot to offer so thanks in advance.