gah dam those prices are low....just remember you get what you pay for...when it comes to performance it might be better to pay a lil more for it....and especially with the lowering springs, it might feel like crap if you buy those, im not sure, but my friend bought some ebay springs and they ride so hard, hate when we hit bumps or anything, i would personally suggest
an AEM Intake
DC Sport Headers
i like 5zigen or you can always go with APEXI or Greddy Evo series exhaust
and Ground Control Coilovers

well let me take that back with the intake, most intakes will give you about the same result, some respond better then others....but with others you might want to consider, the Greddy Evo, 5zigen and APEXI give your cars a deep nice sound to it

oh and thanks for the compliment