What is the highest possible break in snooker?

100
38
127
109
147
198
155
189
The term "maximum break" refers to the break of 147, but it's not the highest possible one. If the players get a free ball on full table and pots on of the colors as red and follow with black, he can score additional 8 points, which makes 155 together. Unfortunately noone has done it in a competition match yet.
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