My son's SX'4 had an exhaust leak from the manifold to header pipe that was present after initial cold start-up. I finally was able to remove the nuts and take off the header pipe. The pipe mounting surface looks good. The exhaust manifold doesn't need a separate donut as it has the concave mounting surface. Anything that I can do to improve sealing when I bolt it back together? I was thinking about applying some Copper RTV around the exhaust pipe flange. Not sure if it would hold up in this application.
I've decided to not use high temp RTV for reassembly. Did some research on the web and spoke with the folks at Wurth. I think that I'm going to give their exhaust assembly paste a try. The rep that I spoke with said that it was a perfect application for this job. I'll report back once the car is up and running.
http://www.shopwurthusa.com/wurthstorefront/Chemical-Product/Miscellaneous/Exhaust-Assembly-Paste-4-94-Fl-Oz-Tube/p/0890100045#
Good luck! I'm interested to hear how the paste works. When I first got my car running, I had an exhaust leak at the same spot. Turned out the first shop just did a poor job of getting the nuts tightened on there good. Second shop had it fixed in no time.
The link states that the paste becomes metal hard and seal permanently. I'd be worried about not being able to separate the exhaust after using that stuff.
I asked the manufacturer about whether the parts could be taken apart and if the sealant could be removed if necessary. I was told that parts can be removed. and that it can be removed using a grinding stone or flap wheel.