The first generation could be modified by moving the sensor and magnet, but since then the only way to change performance AFAIK are with "dongles" sold by some companies (the one I know of - for Yamaha systems - is in Europe). I use my bike only off road, so the performance is fine. If you want a fast street bike, you can build one very inexpensively with a direct drive system.
Assume you have the Bosch "small front chainring" so you can't use the "narrow/wide" ones, but maybe you can increase the tension screw on the rear derailleur or remove some links from the chain to reduce the incidence of derailing.