done a coupe or runs on the road awhile back. same part of the road. each starting about 3000rpm and finishing at 7400 (limter) in 3rd gear. then over layed them. one of the graphs is on flat road one is done on a hill. so they nowhere near perfect being done on the road. but gives an idea.
dotted line no wi. solid with 100% water, water wi comes on aroud the 4 sec point. you can see the change in afr
so you can see it does lean the afr slightly. less at hig revs as its only single stage setup.
its not a great deal diffrent, thats probably why i didnt notice it while just watching the guage.