After driving normally then "occasionally" really get down on it I get the usual dusting out the back. I notice it especially after a 200 mile highway trip. Now before I "carefully" removed the soot where was it exactly in the exhaust system. Pre-turbo, in the turbo, post-turbo, in the kitty? Just wondering, probably after the kitty would be my guess.

 

I would take a guess it builds up in the muffler. If the muffler is just baffles, you wouldn't have a much as if it has sound absorbing materials.

 

post turbo ,cat and muffler

especially the cat

 

That does make sense. The truck seems to run a little better after clearing it out, it doesn't take much to clear it either. As long as I don't do it too much, MPG seems to climb slightly. Thanks..I was just wondering.