90% of the time the wrench just follows the direction of the pipe manufacturers carb settings, regardless of what type air intake you have. They err on the side of caution which is always rich. In time, fouled plugs, excessive carbon on pistons, eventual loss of power, detonation due to carbon. If they have you jet too lean, could actually put holes in pistons. Usually they richen the pilot ckt with a too large a pilot jet and too large a main jet. What you also need to be aware of is if they changed the air bleed jet. If you'll notice that at cruise speed your throttle is not past 1/4 throttle. Cruise mileage is mostly from gas from the pilot ckt at this point, and also determined by the diameter of the needle in the needle jet (needle jet is never changed) Myself, I use 65mph to determine my cruise mpg's, same speed in which Mikuni uses in their testing. I also use AFR monitoring to determine my jetting, over the years of reading carb posts (over 5k post I've read), and various issues associated, seeing many a peoples dyna runs w/AFR monitoring, I started to see a pattern where an AFR of 14 yields 50mpg. I did find an article that makes a lot of sense in carb tuning, most of the article is geared toward HD engines, but AFR is AFR, and it certainly worked for me following their AFR table. I did use the leaner of the AFR spread they show in each ckt to preserve my economy vs performance, though performance is not bad either. I've played quite a bit with my carb setting just to see what is what. I did notice that full point richer in afr, a seat of the pants difference, but only a half point richer was much harder to feel by seat of the pants. I was never able to tell proper main jet selection regardless of methods I tried, when I thought I was spot on, to only find that I was lean when doing the AFR monitoring. Hence I started to do more monitored runs. One of the most important things is to make sure there are ZERO air and or vacuum leaks on the intake.
here's the article: http://www.daytona-sensors.com/tech_tuning.html