LOL.. surbo is just a piece of metal with fins... not moving.. if anything it just restrict air intake some more lah.. there was a guy in.. err some car forum (forgot) with nick RM1.. did DIY it from aluminium can to his toyota seg A101.. he says got feel something (dono psychological or not).. but definitely NOT save fuel..
Please understand this equation:
More Power = More Fuel
Save Fuel = No Power
But bear in mind, this piece of thing MIGHT give a result (more power) on carburated engine. since in carb engine the fuel coming in is not a sprayed mist (as in fuel injection system), the fins help to create some sort of turbulence vortex of wind which splits the fuel into more finer mists. i guess this is why a lot of people said it really works. but for EFI engine, dun bother. My opi only.