From trolling through the archives, I note several references to exhaust gases leaking by slip joints.
My engine is a Lycoming IO360 180hp and the exhaust system came from Lancair. At 44hrs I removed my cowl for various inspections and
for the first time was surprised to see evidence of exhaust soot on the lower right cowl area. There is little to no discoloration due to heat, just grey, blackish soot and not much. The location is about 23" forward of the firewall and offset about 8" to the right of center. My first thought was that the heat muff was suspect, but no. This condition was not noticeable at the 25hr oil change. All four pipes are fine, no cracks, etc. But there is clearly some leakage at the slip joints where the pipes crossover from right to left. My local A&P says this is typical but my skepticism grows with age. I've read and heard negative comments about coating exhaust pipes inside or out.
Is there anything more to do other than keep an eye on this situation?

Thanks,

Angier Ames
N4ZQ
44hrs