2011 v6 gears 3.55

I just installed 3.55s in my 2011 V6 Automatic, and assuming the cars mpg calculator isn't thrown off like the speedo, I'm getting 24 mpg in the city, compared to 17-19 with my 2.73s. I also have a JLT intake, which seems to give me an mpg or two of efficiency.I haven't worn the gears in enough...