Although i'm not quite in everyone else's league as far as mods go (yet...) my Pro-M 87mm MAF definately helped. From what i've done so far, the MAF might seem like a waste of money but I got it very cheap along with FMS pulleys so I couldn't pass up the deal. Setting aside all the little pro's and con's of both meters I would think either would be a good choice.
Gains? Who knows. It definatley feels faster but i've never had it on a dyno.
Brett
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66 Tahoe Turquoise Coupe
Laser Red 96GT Ragtop
30 Years & 30 inches apart in the driveway!