Adding a new Setback Bracket

Well, after a long hiatus from dialing in my Pulsare 2100/Merc 225Xri, I'm finally going to make a change. I've purchased a 8" Stainless Marine Setback bracket to install on my Pulsare. With my Bob's Hyd. Jackplate I'll then have 13.5" of setback. I ran last weekend 74.3 mph on GPS turning a Trophy Plus 26 at 6900rpm with 7.5" setback. I think I could hit 75-78 mph consistanly with the additional setback.