So my S4 has more things done to it than i know and im always learning new stuff , it has all the wiring to be an s4 , its a t2 btw. Though the whole turbo and exhaust system is s5 im rebuilding my emissions harness to do everything except the emissions because they are gone so why leave unuse wires all across the engine bay tuck at random, there has been many necessary systems i have had to rewire properly(previous owner hacked cut and left,as in he left cuz he couldnt get it to work properly) anyways im now wondering what has been done to the block?this car is nuts very loud and extremely fast(4600 in 4th and i slow down). so if you look at my irons that is where my knock sensor is above T2,and i have read this makes it an s5 block, but im not sure if s5 and s4 middle irons are interchangable. does anyone have side by side comparisons?

 

They are interchangable between s5 and s4 tii's. S5 have the knock sensor located on the front housing. But imo, the stock knock sensor is garbage.

 

thats cool , im just trying to figure what block i have or if the one i have is piecemealed from s4 and s5 parts