The problem of sooting up has been corrected. I am a diesle tech at a local dodge dealer, the o7 6.7L cummins is the one that has the biggest problem, basically cummins has installed an egr valve onto the vehicle. This egr valve now brings exhaust gasses back into the intake manifold, with this recirculation all components in the exhaust are getting extremely sooted up,the main part that gets sooted is the turbocharger, and with cummins incorporating the exhaust brake into the turbo we now have faulty exhaust brakes, the fix is to completely clean out the exhaust system ,replace the turbo and update the ecm, with all this the problem is resolved. I now have about 8 6.7L turbochargers that i am looking to get rid of, they have been cleaned, one is off an 08 and nothing is wrong with it, it has 2,000 miles on it