Light doesn't always mean fast. There is a LOT to consider. My Fishing boat is a 17' ski boat and it weighs #825 and is a slug compared to a 900# 19' bullet with the same engine.
Shane,
that engines begins to fall off a little past 6500 and as you see it pulls HARD to it with all the modifications that was done to it but you may be going to wrong route. You may want to go gearcase change then prop. If you change your gearcase it will tone down the RPM's and will increase in speed with the same prop. You need to run the 1:87 case I have here of Wes' and use the 23 laser and see what it does. Just my thoughts. I also have a 25 Tempest you can come get and try if you want.