There are a lot of variables in the hookah system but, the volume of air, speed of that air, heat, etc. all dictate the density of the smoke generated. The hose restriction whether wide, narrow or somewhere in between is only one variable in this process.
I would say prove my theory wrong but based on the limitations of a system (hookah) you will have a sweet spot for how much smoke you can generate creating the most dense cloud possible. The rate at which you pull that smoke off the tobacco, suck it through the tubing system and, eventually lungs, will dictate the density of that smoke.
Here I will get you started off in the right direction: http://chemistry.bd.psu.edu/aronne/Air%20S%2705.pdf
CFM calculator: http://www.engineeringtoolbox.com/sc...fm-d_1012.html