OK, completed my trip with the new exhaust.
First leg of the trip was pulling an 18 ft camper trailer, and I managed to get 20 mpg, about 1.5 - 2 mpg better than with the factory exhaust.
The return trip, I did not have the trailer in tow, but had a very strong head wind, and I was in a bit of a hurry, so my speed was a bit more than it should have been, but I still managed 31.25 mpg, again about a 1 - 2 mpg improvement over the stock system.
The exhaust note has not gotten any louder, even with 700 miles on it.
This is a great system, reasonable price, good quality, adds performance without the noise.