i find that any fuel booster or additives wont last long. is just like ladies trying to look young using stuff like sk2 and so on. yes it does work, but when u stop using it, the effect is even worst than before u even started using it.. if u get wat i mean. so if u stop using those addictives, u would find that your car will have higher FC compare to before u started using the product..
just my 2 cents and no offense to SK2 LOL