I was reading the link from HeyYou and it seems they were using this mod to potentially increase MPG. Did any of you members that installed this notice any sort of increase in MPG?

 

Nope and I don't see how it can, the rear (post cat) O2 sensor has nothing to do with the a/f ratio, it simply reports that the cat is operating within specification parameters. Not having this sensor simply triggers an annoying CEL, but does not effect performance in any way. The non-fouler trick just moves this sensor down and out of the mainstream of the exhaust where the air is a little cleaner, appearing that a cat is there cleaning the exhaust fumes...