I've read that with the pro kit its your choice because you're only going to lower the vehicle about 1.5" an you may still be within spec. If you're going with sportline, I would definitely get the kit if you want even tire wear. That's just what I've read. I haven't lowered my car yet so I can't give you any first hand knowledge.
I just Put On H&R springs and I was told to break them in before doing ANY alinement becuse the springs will settle a tad more BUT I Love the stance it has now!
Also the guy at the shop said i was in Spec as it stands and buying the c.c. plates was up to me BUT not needed!
So I say put the spings in and drive it for a bit and see But I'll tell you this the H&R's are about as Low as you can go and if My 03 GT is in spec with them then so SHOULD yours.
If some one tells me How to post a Pic I will to show how it looks
Thanks
Andy