I have a 2001 chevrolet silverado z-71 extended cab without onstar and has a completely stock audio system. I will eventually replace everything but need your advice on what to start with first. I'm thinking about putting a sub in first. I will most likely only want one sub since I dont want to shake the whole neighborhood. I dont have a lot of room under my seat( about 11-12 inches)so what kind of box would you recommend? Also, what brand and size of sub would you recommend? I know price pays a large factor in quality but if possible I would like to get a sub and amp for around 200-300. my next question is if I should replace my HU or just upgrade speakers. I was looking at the alpine cda-9827 but wasnt sure if it would be a noticable upgrade over stock? what speakers would you recommend? I like the infinity speakers and they are a decent price, but im not sure if they are they great. I'm open to any suggestions and opinions on what i should get. I understand that when dealing with audio its all up to the individuals own personal taste, but a point in the right direction would be most appeciated.