Before revision:  Setting the maximum  rate to 0.30-0.40 (as in U.S. currently) leads to an exponent of 1.5-1.8, while counterfactually setting it to 0.8 (as suggested by Piketty, 2014) would lead to an exponent of 2.6.
After revision:  Setting the maximum tax rate to 0.30-0.40 (as in U.S. currently) leads to an exponent of 1.5-1.8, while counterfactually setting it to 0.8 (as suggested by Piketty, 2014) would lead to an exponent of 2.6.