an m90 is a roots style supercharger is it not? in that case it most definitely can pump air in reverse order.. its just a simple air pump.. just have to get the pulley to go the opposite way.. which can be done not necessarily just by running the belt over it with a flat pulley.. not sure how he does it though so i can't be sure..
2003 3.8L V6 4R70W
Windstar Upper Intake with cool-air intake, MAC LT headers, BBK O/R H-pipe, and flow 40s, SCT tuner, FRPP Alum. D/S, 3.73 gears, Auburn HP limited slip, and Team Z LCAs, Eibach sway bars.
Best 1/4 time: 15.036 @90.92mph, 2.148 60'