i bought a 2nd hand one and it gave me an additional 1.5km/L. pwede na. around 12-15% saving yata. but BS yung up to 50% savings
i also have to change the filter (green scrub pad lang) every 6 months
i've researched about it. the theory is correct but the mechanics to fully achieve this on the device is not perfect. it does work to a cetain extent.
unfortunately, you could tune your car and produced the same thing.
it only works on carb engines pero may nakita ako sa VTI
i've also seen a device for deisel engines pero hindi khaos.... but that's a different story