There are a pile of electric superchargers out there these days. They mostly seem like the one on the link below, but this looks like a home grown version
http://www.esuperchargers.com/
If you believe the advertising its gets a 1-2 PSI manifold pressure increase and so should give a few HP. It looks like its mounted on Carbies so I wonder if they lean out when the fan is swithed on. When you set up a real supercharger with carbies downstream they have to be specially set up for "blow through". Otherwise the extra pressure in the venturi stops the carby sucking fuel properly and it leans out. These electric pumps are probably so weak you could just set it up a bit rich and it would be OK.
Regards
John