While I think the % increase are way hyped (if any increase at all )
But looking at this page data doesn't give them good impression IMO .
nanotechnology.qmax nano Fuel Saver Manufacturer,Qmax nanotechnology products, aftermarket performance parts to increase horsepower, less pollution, smoother engine, engine response, deisel common rail engine, petrol engine
Look at the bottom chart data before an after .
Note ; gear = before 4 , after 5
not sure what tour/min = maybe rpm but if that's not a typo it is not exactly fair comparison .
If the car has bad/corrosive ground points I can see grounding cabling helping , then again you could just fix the bad area to bring it back to OEM spec .