power service cetane booster is a petroleum based product with aromatics and nitrates. These products are known carcinogens and simply increase temperatures without really increasing power.
Like socom says ethanol is an oxygenate added to our fuel to reduce CO and increase fuel mileage in the winter months and now more and more often. Unfortunately ethanol has no heat of combustion and produces no energy for propulsion therefore your fuel mileage decreases...similar to using power service.
It depends what your looking for. If you want added power, you need to boost more or take in more oxygen basically with an air intake or an oxygenating fuel additve. You need to look for a detergent fuel additive that will keep your fuel system clean also.