Engine vibration may be due to weakening engine mounts. The scan that santro guys are performing if Ok means your engine is healthy and emmissions are under limits. After 30-40k kilometers replace your timing belt, and get your valve clearence adjusted. As there is no carburettor in efi you dont have to worry about mixture deviations/ tuning, ECU manages that automatically .. As u have decided to buy EFI , it manages most of the stuff, replace plugs on time and i suggest not taking the vehicle to a common garage as they will spoil your engine and stick to huandai experts. I am sure the'll be able to identify the noise problem that would propably have nothing to do with tuning. If u have CNG get your Timing Advance Processor Also Checked!!