How is this supposed to increase horsepower and torque and save fuel ?

[cas951]

Actually there are use cases for this specially on older cars where ground points and ground cables have corroded over time. In my case my 88 944 turbo S needed this to fix fluctuating gauges in the dash and headlight. Adding additional ground points really helped my issues. Gaining HP? I don't know where that came from but maybe if you have ground issues with your ignition system this may help this as well.