Ok so the speedo is 5mph slow. I do 70 mph at around 2400 or so. I can bottom the speedo by 3k rpm. Only did that once or so. I took the truck on my grueling test track yesterday morning (section of 17w in NY state, west of woortsboro) where there is a good 3 or so miles long incline where semis have to drive with hazards in the right lane, barely climbing this darn hill. I could barely hold 50ish prior. I can now hold 65 and actually increase speed if I want to but I go by the egt gauge. Stayed in at around 1100 climbing in 5th gear holding 65mph, so hugeee improvement. As far as drivability, it's faster and more responsive, love it. Mpg's I noticed can go as high as 24 if I stay below 2k rpm. I average about 21 but if I keep with traffic and go around 70 mph, which is where I drive while on the interstate, then 17 to 18 is what I get. Bottom line is, it's a different truck now and I'm not sorry to have put a hole in the hood. It's all worth it.