Mr. Corsair23 and I did my MAF mod yesterday evening. Not hard at all. The truck immediately ran better, just based on my own experience driving the truck every day. No hesitation off the line, smoother operation and shifting. Also, seems like it gained some power too.
I'm running 35-inch tires with 4.88 gears. No supercharger. It's a 1996. I stopped tracking mileage a few months ago, since my speedo is significantly off. I'll use the GPS to track mileage out to the Rubithon and get some numbers.
Honestly, I don't care about gas mileage in my 80 as much as I want more power. All the weight I've added to the truck has made it a beast. If I could find a supercharger, I'd probably buy it.
All in all, I think the MAF mod was worth every penny.