hey guys, did a quick search but couldn't find anyting really useful

i just bought 18" mags, i'll post photos of them soon, cause i'm not sure what they are called but basicly look like this http://www.ozzytyres.com.au/wheels_m...=115&mag_id=71 but not as black. on the bill it says Raze Shadow


Anyway i really need to lower my car but really have no idea what springs, by how much, the cost and who i should be getting it done from. At the front there is a lot of room for me to lower however at the back chances of me scraping the side are quite high. Any advice