Agree with all of Tod's suggestions & paints Rick. Wurth used to make a grey exhaust paint that was a match, but stopped making it about a year or so ago.
This was the link to it at NLA Ltd. (for the 356 folks), which is dead now & when I checked in Spring they didn't know if or when they may get it again:
http://www.nlaparts.com/store/exhaust-grey-paint-p-653.htmlMaybe someone in P-cars near you has enough in their old stock for a small job like your "S-tubes"? ...I think the 653 in the link above may be the old Wurth part/color no. to help you track some down?
Otherwise, maybe NLA can get it custom matched like these colors at the link below, or try emailing them to see what they're 356 CWs are using now.
http://www.nlaparts.com/store/356bt6-acces...87_114_252.htmlYou can also try these HT Paints to see if they're closer (2 flat greys), but try them out in a test patch & match it to the muffler or something with the original exhaust grey intact:
http://www.vhtpaint.com/products/flameproof/Tod may have tried these already - if so, hopefully he'll chime in.
I too got the SSI HEs & J-Tubes for my 73 2.0 - but not the "S-tubes in SS as yet, so let me know if you hear of an extra set, but do yours first cuz my resto is a long way off from needing them!
Hope this helps!