http://i420.photobucket.com/albums/pp282/GT_160/theboat027-2.jpghttp://www.youtube.com/watch?v=x9yLe6F9FfUThis may help. I found an old video. This is two Canadian 71-75 GT160 owners. The blue boat is runing a 140hp. I have talked to the owner of the yellow boat, with the 115hp merc. He now claims a realistic 55mph/GPS. That is on a well tuned engine, good setup, and prop, and by the dates of the video a few years to fine tune the setup. The owner of the yellow boat thinks 55mph is fast enough, any faster and the chin walk becomes dangers. I am no engineer but it is looking like 55mph is the safe limit for our boats. Watch the video closely and you will see the blue boat is running the same speed but the front of the boat is chin walking/rocking side to side at times. Trust me you do not want to feel the feeling I had as the boat threw me out of the seat. Thank God for kill switches especially for those of us testing the speed limits of old boats.
Still a little hope for more speed
Adding weight to the front of the boat may help a little
My prop and many of the new props are designed to lift the front end of longer heaver bass boat out of the water. My liter old 16 foot boat is safer in the water, and to wild standing on the prop (back to prop testing)