Here’s a link to a pretty good study on fuel economy for a 2006.  The data set is large enough to be credible and probably includes stock bikes and modified.  So it is what it is - a mish mash.  I was interested to see an actual study and not just manufacturer claimed figures.  I have a 2006 with a Keihin PWK40 carb, stock air box with cover removed, and Jardine exhaust.  I’ve just started calculating my MPG this spring after the modifications and other tuning.  After 2 refills, I’m averaging 38mpg.  I do what might be called “suburban riding” in NW Houston - not exactly city, definitely not highway, but some boulevards I can sometimes get a happy right hand on in 2nd/3rd gear.  I’m thinking my number are respectable given how and where I ride.  Sharing to gauge others reactions.  Happy trails.        https://www.fuelly.com/motorcycle/suzuki/s40_boulevard/2006#:~:text=Based%20o....