When someone states a mpg drop or increase, I am naturally a skeptic. Was the drop measured from just one tank, or was it an average drop after at least 3-4 tanks, compared to at least 3-4 tanks averaged prior, with identical driving habits, etc...
My primary mileage is highway (10-15% rural "city"), and my averages virtually didn't change with the intake swap. By "virtually" I mean that any small change I saw +/- were no different than how average MPG can fluctuate due to many factors.
'12 SE Sport 5Dr |╠╬╝|SGM|203a|Moonroof|17" Paint/Mach Whls|K&N 57S-4000|FFE RMM|Steeda STB, RSB|JBR bushings
'01 ZX3|╠╬╝|Pitch Blk|Prem pkg|Moonroof|SVT Snorkel|SVT Susp|Steeda STS|Z-Eng RMM|Magnaflow exh