Is TapBoost suitable for an electric shower? If so, how many litres per minute would it give?

Some electric showers are restrictive so it is best to check with the manufacturer as you may already be receiving the maximum allowable flow rate. In which case, TapBoost would not be beneficial. If you are not receiving the maximum expected flow rate from your electric shower, HomeBoost is the most compatible for boosting the water to an electric shower. It will deliver up to 12L/min and 1.6 bar.