I noticed a slight loss of acceleration, but this wasn't a fast truck to begin with anyway...2wd quad cab, 3.55 gears, automatic trans, 4500 lbs empty...yea, fast it was not!
as far as mileage, the last time I tried to calculate it, I had dropped to around 12mpg overall, and was so pissed I didn't want to even think about it.
then it dawned on me, that my speedo is now off by about 7%, and I forgot to factor that into my mileage when calculating MPGs.
just last weekend I was on a road trip and clicked off 2 50 mile sections where I reset my trip odometer with a mile marker, and after 50 miles, compared what the odometer read, so I know that I'm off on my mileage by exactly 6.8%
now the next time I calculate my MPGs, I'll know to add 6.8% to the mileage before calculating!
stock tires I was getting about 17 overall, and could get 21 on the highway.