OK this seems like a newb question but I cant find the answer using the search and I can't rememebr clearly from past experiences. If I wanted to run a s4 tii harness and ecu in a s5 car would the body portion of the harness prevent me?

I know Ill change the front cover to the s4 kind and make a custom oil return, but other than that is there any reason it can't be done?