Don't forget the higher the output the more the amp compresses and overdrives, so the dynamic range is reduced. This can have the effect of making lower output pickups be percieved as sounding louder as more harmonics are present.
In terms of voltage the warpig is highest, but you may find the frequency response of another pickup gives you more volume in the frequency band you need, for example the Miracle Man has a tighter bass but more low mid than a Warpig.