will an S5 upper intake manifold fit on an s4?

 

The middle and upper? yes, but you have to remove one of the studs on the s4 manifold for the middle s5 to fit. You also have to remove and blockoff the s4 EGR valve, and grind off a bit of metal on the s4 block rear iron. You may or may not be able to keep your stock vacuum rack and maintain stock emissions as wel...I wouldnt try, personally, I'd just run bare block, but that may not be an option for you.