Infinity is only a faint shadow of what it once was. Their Beta line was the pinnacle of their existence. If you want the same basic sound quality, but more power handling and better midbass, look at JBL- same company anyway.
For components, I always recommend you build the set yourself from raw drivers. PartsExpress or Madisound are good choices for these, and Madisound will even build you custom crossovers if you so desire- for not much money. Look into Vifa, SCanSpeak, Audax, SEAS ($$$$), Morel, Dynaudio, Focal, etc. These companies actually manufacture the drivers for most car audio companies. MTX and Boston Accoustics are the only "car audio" manufacturers I can think of that actually build their own drivers. Most others are off-the-shelf drivers with someone's pretty stickers placed on them.