Yeah nothing I think compares for the bang for the buck for a skittle, but Sti's arent too expensive to modify. Also I don't believe there will be any changes in the 06 model but many many changes in the 07 model (completely different look, more horsepower etc...) First mods I think for a Sti would be some kind of engine management Ecutek, Utec, or Accessort $600-$1000 probably 30-40 h.p increase. Then turboback exhaust which is downpipe+catback $500-$1100.