http://www.perth-wrx.com/vb/cosmetic...post-here.html
http://www.perth-wrx.com/vb/mechanic...ent-guide.html

Check those,

1) If you are lowering it, 3 options
-different springs
-coilovers
-grinder

2) Will you need to roll the guards
-with 19's probably yes
-what offset is the rims?

3) Will you need coilovers
-How low are you going?

I'm no expert but this is a vague response to a vague question. Have a read through those links and see what other people have done and suggested, whilst you wait for some one who actually knows what they are talking about.

__________________
A man in nature;

"All in relation to nothing. Nothing in relation to infinity. A central point to both, And infinitely far from understanding either."