I don't think that there are too many 50+ mph 20 seacraft around. I know props made a big difference in the handling of my 20MA. Bow lifting props specifically the Michigan Rapture gave my boat really squirrelly handling characteristics (at 40mph). The Mirage Plus and the Highfive gave the boat entirely different handling characteristics . . . The boat was rock solid up to 52mph with the mirage plus. You might try changing props . . .
The bracket is another variable which effects performance. I'm very pleased with the performance of my 20 seafari with a bracket up to it's top speed 48mph. I don't even have trim tabs and the ride is stable (mirage plus 17P, 26" setback, and 1.87 gear ratio). The weight of the seafari is further forward . . . but the hull really lifts out of the water as you can see in this photo (@ 35mph). You might have hit the threshold where you need bigger tabs or wedges . . . I'm sure the bracket and the additional weight hanging off the transom offsets the engineered balance of the hull. . . but I think you're probably charting new territory for the board as far as the behavior of a bracketed 20 above 55mph. Good Luck!! I'm interested to see what you come up with . . .
