Generally no.  We have heard of hacks that move or remove the top speed limitations or artificially change the wheel size to gain more top speed assist.  However, these hacks generally result in a loss of torque and take fun and performance out of the system in the areas and speeds you ride most.  If you are already over 20mph, most likely you are flying down hill and don’t need more assist.  If you climbing up hill and you’ve gone over 20mph, then congratulations, you are one incredibly fit individual, and you also don’t need additional assist.  Although it’s in our nature to always want a little more, in the long run, it’s best to make sure that your Shuttle remains the Class 1 eMTB that it was intended to be and can be ridden in more places without a negative impact on trail access.  Additionally, leaving your drive unit stock means that your warranty will stay intact.  The Shuttle was not designed or tested to be run with a setting that is more powerful and/or changes or removes the top speed limits for the battery assist.  Changes in the stock system will void the warranty not just of the system but of your entire bike.