[1985 CCX]

Getting close to my headers too.
My headers are already made with outside collector. What style collector are you using, inside the body?
I think as far as difficulty outside is the most time consuming, then inside body then inside body with flat flange.
CSX3006 showing the outside version, CSX3016R shows the just inside collector. Guessing, no facts, SAI ran early cars outside as it allowed the side pipe changes to be easier.
I'll snap a photo of the pipes I have, my HTM will be outside, my other car inside...
Outside collector requires in and out a few times. The inside body can be easier and Craig C makes them for a HT car if you wanted a fast forward button.

Planning to go through that process on this platform however mine is more extend what is there as its my last hurdle then gas, battery and drive.