NA 6 port s4 vs. S5
 

Hey everybody, ive got an s4 na im rebuilding and ive gotta get another center iron. So i found somebody with one in good condition but he doesnt know if its s4 or s5. So ive got two questions.
1. Is there a difference between the two? If so what?
2. If there is a difference, will they still work with eachother?
Thank you for any information!

1. Yes. the S4 has the EGR stuff on top, and the S5 has the air injection port under the intake ports, S4 just has a freeze plug there.
2. if emissions isn't a problem, then yes. i think the S5 iron might let you keep the air injection, the S4 uses the end irons. EGR will be gone, but it doesn't do anything, if needed the bolt holes are there. so fi you need emissions, you need to verify the air injection still works, it should, but needs to be checked.

Emissions are ot an issue. So they will work together if im not worried worried about emissions?