Hello,

I have a '07 LBZ Duramax, 93k miles. Bought it used @ 72K. No problems with it, love the truck. I travel for a living and so I pull a trailer. I used to have a bumper pull and have recently upgraded to a 5th wheel. GVWR: 15,500 - we are likely just under that weight.

The issue: Black soot! I don't have a power loss, but just lots and lots of soot, under a load. The 5th wheel is new and I had a few warranty issues so I took it in. The service manager told me that he had NEVER seen that much soot on a unit (5th wheel). I don't have a chip or programmer on the truck. As far as I know, it has never been programmed or flashed. (although it is possible, I am the 3rd owner.)

I did put on a Flowmaster HushPower muffler and an Injen Technologies Cold Air Intake several a couple of years ago and was very happy with performance increase. The cat I left alone.

Any ideas folks? The RV Service Manager is suggesting I take it to a dealer as he believes there is a problem. The soot is a problem, sometimes it is hard to get off of the unit.