The pump is actually a quick responding setup Dave - Not as precise as the solenoid but very capable of keeping mixture in check - Im thinking the feedback from the rpm is helping in this regard but I have seen no delay issues with the response. Remember we are talking less than 1psi and the changes happen quick and very repeatable as its a positive displacement pump. I'm not sure if Acceleration function is needed with the air pump as I think by what I have seen it helps in this regard.

here are some pics of the module unit - Slightly bigger than a standard servo and about the same weight. simple hookup - one to ignition and one to open channel - air line to vent of tank.