I was told mine was -1 in the rear (previously a nitrous bike so it was to keep the front wheel down)
no speedo healer needed because my 95 has the speedo cable going to the front wheel.
haven't put enough cruising miles on it to know the milage myself, but previous owner said he could get 50 if he went easy on it.

 

I know mine went down. Before the change i was getting about 120 miles before my light came on. After my sprocket change the light still comes on aroudn 120 and I havn't put the speedo healer on yet.