Nice clean installation, you should be proud.
One question, does the muffler have a baffle ,reason I ask is DD cannot have muffler with baffle as that will make it consume oil. One of my customers had a 6-71 in an emoryville, he came in complaining about using oil. He also went to the local DD distributor ,their question was did you change the muffler. He had put one from a mack on it ,they told him to replace it with an open thru with resonant chambers and your problem will go away . It did.