Personly some JL subs are some of the best you can get. And Boston acoustic knows how to make some really good subs, their subs are load as crap but still sound really good, you just have to have a big amp for the subs. I sat in Boston's bug at NOPI and that was one of the best cars that I have ever heard. Their pro line speakers are really good.Infinity kappa speakers also sound really good. A lot of people here will reconmend differnt brands but the best advice I can give you is to go to a local car audio show and sit in the cars and listen to them to see what you like the best. Even if you cant do that go to stores and listen to their stuff, just dont go to best buy, their stuff sucks.
---chris