I certainly noticed better performance when i fitted the KaN the car drives a lot better than with out it, .but as for MPG i would not say there was any improvement at all, Or not according too my trip computer anyway. My average mpg was 39.9, with out KaN, now its on average 38.5, not a lot of difference but its never gone back too 39mpg or above since it was fitted, may be my engine is loosening up. I have just gone too 12k on the clock, or the Vmax has somehow cleaned out my engine it certainly feels a lot better when on it for sure, or maybe its just shell fuel. or maybe its just me.