Nice job Jeff. The question was asked about filtering the vent, being that it looks like you installed the same kind of vent that I did. All I did was fold up some paper towel several times, and ti-wrap it to the vent. This thing doesn't need to breath alot of air, so it should be fine. I haven't any trouble since I vented mine.
Bellweather: there is a vent under the seat of the 2200........that was my next modification if Kubota hadn't done it from the factory. As others have mentioned, you just need to hear the gasp of air once when opening the dip stick on the front axle to realize the pressure that can build here. As Jeff mentioned, it doesn't take long to do this little mod.