If your wanting to go N/A then (I personally)
Would start of with a S4 GXL..
Why?
4 piston calipers in the front.
OEM LSD
power windows (cause im lazy like that)
You are going to have some people tell you to start off with a SE (base model)But then you would have to do the 5 lug swap,LSD etc etc.. but it will be a little lighter.