Any custom audio shop recommendations?

[usctrojan]

I just purchased a 2007 G35 Sedan and don't like the stock audio system sound at all. I don't want to mess with the head unit at all since it is all connected with the nav and I like the interior look already. At a minimum I want to change out all of the speakers. But I would like to take it a step farther and add an amp and subwoofer to get a full range sound. The problem is I really don't want a big box sitting in my trunk. I see all those show cars with custom mounting into the floor boards with speakers shown through plexiglass, amplifiers highlighted with neon, etc. I don't want a show/competition car, but I would like a clean professional simple custom install to mount the speakers and amps and whatever unobtrusively. Does anyone have any recommendations on an outfit in Southern California I can look up? Preferably in Orange County.