JP.. I would be leary of that car. The guy is asking way too much for it in my opinion. Yes he has done alot to it, but by that same token you don't have any idea how hard it has been driven or how good the quality of workmanship is. You also mentioned in another post that you were sick of modding cars. Well.... this one is modded to he11 and back. It could cause problems for you in the long run. The longevity of the engine is going to be far less than stock. You are paying far above market value for a car that will be less reliable, to some extent or another. What exactly is your goal in buying a car? In other words what are you looking to do with it? Give me a percentage totaling 100% from the following categories. reliability - style - performance. I think I already have an idea as to what you are looking to spend.
Also. When you say S4 I think Porsche. But I have a feeling you are referring to something else. There is also an S4 BMW and an S4 Audi. Please enlighten me.