Foaming vs. beer style

I'd like to know if folks are experiencing foaming with certain beer styles.

I just set up a 5 tap keezer and now have beer flowing to all 5! (wo hoo!). Anyway, all gas lines come from a single manifold (set at 17 psi), with the same hose and lengths to the kegs. The beer lines are all 3/16 ID, 6' long. Each keg diptube has an 1/8" ID plastic line insert, all same length. All faucets are the same model of Perlick's. Shanks are same length. Here is what I'm observing:

ESB, 48 IBU, 1010FG, 1/2 glass of foam
Bock, 29 IBU, 1022FG, perfect foam
Belgian IPA, 48 IBU, 1008FG, 1/4 glass of foam
Amer. IPA, 54 IBU, 1011FG, 3/4 glass of foam
Hefe, 26 IBU, 1015FG, perfect foam

My immediate assumptions are that higher hopping may be contributing to increased foaming and maybe the lower gravities as well (except for the Belgian IPA). Is anyone else seeing this? Since hoppier beer increases foam, this may be the case, no? And lower gravities hold more CO2? As time goes on I will hopefully recognize a solid trend and figure it out. But in the mean time, I'd like to hear from others on this issue.

Thanks!

Well, I snooped inside the keezer yesterday and did notice that the two foamiest taps have gas lines going to the part of the manifold closest to the gas supply line, which are of a slightly different design. You see, my manifold is made from two manifolds; one has 2 ports, the other has 3 ports with a pipe between. The 2 port manifold is brass and slightly smaller than the 3 port, which is stainless steel. I didn't think this would make a difference, but perhaps there is a pressure gradient from one to the other. I switched lines around and will see if I notice a change.

Any thoughts on this would be most welcome.