"half packed" is how they come from the factory. the rear section of perforated tube/ endcap is the difference between FX, FS, and FE.
FX is straight through. FE has a tortured path as such to create direction changes in the gas flow and thus remove a bit of noise.
Incidently.... have you thought about how the packing is still in there if its only "half packed"?
Looks like you have a straight through tube on yours (common performance change) that somebody has already modified.
I base my comments on the 2004 model.