Your thinking of springs, not coilovers. Coilovers come complete with the shocks/struts, springs reuse the stock shocks/struts, thats when those go bad after a year, yes, you will shell out about $800, so add in the sprigs, $250, you have just bought a set of KSports or Tein Coilovers. Honestly, on the performance spectrum, not much gains from stuff, but the Injen intake and exhaust should do you over, the ksports are $925, so you could get those and have some for wheels. Ypur honestly looking at thousands of $$$$$$ to really mod your E with anything worth while due to you will need a fuel management system to run any big non bolt on changes.