I would get tires first, then upgrade your brake system, and dont foret the fluid(i use motul). Everyone always goes and buys all this adjustable shit and dont know how to tune it. Im guessing your just getting into this? So spend the money on what counts.

For brakes I have integra front, which is basically what you have on your SI. i use powerslot rotors, hawk hp+ pads, and Motul RBF-600 fluid.

For suspension i have H&R Race springs with tokiko blue shocks and some generic upper strut bars on my car. Its not the best thing out there, but ill tell you ill hand alot of cars and some bikes their asses(this is with a single cam too )

but like i said, get tires, brakes(rotors,pads,fluid,stainless lines), and droppin it some wont hurt.