I have been told that the Nicson exhaust flowed terrible. I have a webshots album of my exhaust setup here ->
http://pets.webshots.com/photo/2621544980030346325BeKaJR I am sure they flow better than the stock exhaust, but not sure how much worse than a set of Fentons or tube headers. I like the look and for now that is enough.
I am switching to Nicson 3-carb intake when I get some time. The motor pulls strong now and has no problem sending the truck with stock stance over 90 mph - drum brakes make me a little queasy going any faster.
My present shop project is putting in an overhead crane - as soon as that project is done, I am on to the casting furnace. Too many projects, not enough time.