I used the Vance 2" set back manual jack plate specifically designed for jets and loved it. Eventually I did some angle measuring and decided that the height of my 115/80 merc wasn't the issue. The attach angle of my 115/80 merc and my previous 90/60 etc attack angle were way off. My merc was sitting at a lesser angle which was causing the problem. So orderd a 2" wedge from Vance and now it's spot on without the jack plate. But really loved that plate when I had it. It was rated up to 115hp.
I believe I posted it for sale on here to a while back.