Well today on my drive from colorado to wyoming I was merging onto the highway, mashed the pedal, got up to speed, next time I rolled on the throttle I noticed an exhaust leak type noise coming from the passenger side. Pull over check obvious things, EGT probe, manifold, downpipe clamps..ect. Nothing, look for soot to clue me in and there isnt any. The noise wasnt apparent at idle, only when applying throttle. So I start driving again, noise is still there. A while down the road I decide to take another look, this time I took the head shield off the manifold to make sure it wasnt something I couldnt see, still nothing, still cant hear it at idle which is making it very difficult to locate. Some I come down into denver, and decide to look again. This time the exhaust leak sound was very apparent at idle, and tracked it down to around the top of the valve cover and behind the fuel filter and fuel filter bracket. So I take off the bracket (which allows access to the #5 cylinder injector) and sure enough, there was soot all around the injector and its cavity in the valve cover and head. Obviously a injector/combustion chamber sealing issue. :damnit1: I happend to be about 1/2 mile away from ATS so I went up there do decide what to do next, the truck only has 35K and under warrenty so I went on down to the dealer, and they're diag. was the same as mine. So, that is where the truck sits, I cant say exactly what area of the injector failed yet, I should know more on exactly what happened tomorrow. But since GM's parts distribution is here in Denver they did have an injector, so the work is being done and I will be talking with the tech tomorrow and get a personal look at the failed part. I and others believe this to be an issue the derived from when the motor was assembled. So far the is the first incident of this on an LBZ that I know of, I will keep updated.