I would go with the Tower muffler also. It is so cheap and no shipping or handling. Plus it has a good sound to it.

As for a full length pipe you will gain rpm but it will run like a engine with a pipe. From ones I used before being one of them MAC's is that pipes don't like smooth slow gradual transitions. They start off good then get to a point where the pipe kicks in and the rpm's jump. They will jump off and on pipe fast but the smoothness that would be needed say in a hover would not be as pretty.

Maybe all pipes aren't like that but from ones I have they are like that.

Now I have and MVVS pipe on my 77 and it gets up on pipe at a very low rpm. The rest of the throttle range is smooth except for that first burst when it kicks on pipe. Before when I had a different header the pipe was acting against me when trying to hover. I would pull into a hover and it would pull vertical. But if I backed off to steady the hover it would run off the pipe and start to fall. Then I would add to regain vertical and pipe would kick in and it would be to much. I messed around with that over and over and it was agravating. Thats reason I went with another header also.

Oh back to point. That Tower Muffler works good!