Hey man I had the same dilema and here's what I came up with. I ran the South Jersey Region SCCA on April 1st and placed 1st in GS (the stock class). But I hated the wheel gap that the stock suspenion left me with.
I searched lots of posts on here and h-t.com and I found eibach and comptech to be what I was looking for.
I chose the Comptech's
1. They are made by Eibach
2. Realtime Racing came up w/ the specs so they had to be good.
I just mounted the Comptech's on the stock struts and there is a significantly less amount of body roll then stock, so the ride is not harsh because the dampening is the same. I'm waiting for Koni to develop struts for the Si. And that will be my next mod.
I also have a set of Enkei RPF1's and Falken Azenis on the way. Should be here sometime this week.
Keep in mind though that springs will move your car from GS to STX. 06-07 Si's jump STS becasue they have a gear type LSD. You'll be up against 300whp WRX's.
I dont know what part of Jersey your from but you should come out to the Philly SCCA this Sunday.
Heres some pics. Before and After the Comptech's.
Before:
After:
