I also have MG-1. This filter is a low restriction filter, so affect on air delivery, as I experience it, is minimal. It does not matter where the filter is, the best way is before the pump, but there is no visible air inlet on the pump supplied with MG-1, so if I find a way to move the filter there, yes, it would be a logical way to do it. Yes, this filter kepps dust away, which eventually will clog up those tiny holes in MG-1's air tube. Another thing I would put there (and probably will, as NYC is a humid place) is a water trap, which I found on line for about $15, drainable. Also, a nice air tank to smooth out the pulsing (after the pump). And to get really sophisticated, a pressure regulator! BTW, these fuel filters can be had on line for as low as $1.50, but I decided to go to my local auto parts store and actually blow into it and see how restrictive it is. Mine has a paper element inside, similar to large air filters for carburetters and fuel injection. These are the part ## that Bruce suggested:
Pronto - 33011-wix
AC GF-505
Hast GF-95
Puro F21124
PG4164
Mine is a WIX Filter part #33066. No direction flow, nipples are slightly too big (the smallest available, 1/4"), so you have to warm up the clear line's ends carefully with a lighter and they go over easy. Hope this helps.