How brave are you? If sound quality is the #1 goal, port the tourpak. Air flow is critical for sound. If you stifle the air flow you muffle the sound. I have never done a bike but done many cars and home systems. I did a 82 cutlass once and the trunk was so packed that there wasn't enough air flow so we cut two ports into the back dash. Made a heck of a difference.
Are you kind of doing something like this???
It did help with the lower end of the spectrum.
Do some homework and use the correct size ports for the frequency you are trying to achieve. Attachment 499723
That looks interesting. I wonder how much of an interference the back rest plays?