The MM is described has having "smooth hi-mids", perhaps not the best choice for the tone you're after. It also may explain the perceived output difference (BTW, your pots value will impact the hi-end response but not the output level). The Painkiller might have been a better choice if you were looking for a much more middy tone (disclaimer: I tried neither of the MM or PK, it's only from the tone charts, descriptions, and what I know of the ABomb).
I'm personnally quite happy with the ABomb bridge on my SG, but a SG is smaller and thinner than an Explorer and these full mahogany planks are known to easily mud out with mid-hi output alnico 'buckers. But anyway: you do have an ABomb bridge, so you can just try it on your explo and find out how it works for you.
Oh and yes: I assume you double-checked your wiring, pots etc...
