Octane booster usually contains two chemicals. One to raise ocatane, and one that is a detergent that helps to clean the injectors and fuel system. As stated above, you don't really need octane booster unless if you need to raise your octane.
However, the part about cleaning the fuel system is actually something that shouldn't be overlooked. At every tank, I treat my fuel with Lucas upper cylinder lubricant. Its a mixture of petroleum slick oil, detergents, and a formula that allows gasoline to combust easier. The slick oils lubricates the valves, rings, and upper cylinders allowing for easier piston and valve travel and the detergents keep the gasoline clean as well as the fuel system. This stuff actually works. I get about 30-40 extra miles per tank with it and it's not that expensive. I buy a 32oz. bottle of the stuff for about 7 bucks. It treats about 5 tanks of fuel for me. 5 tanks times 30-40 miles per tank = 150-200 miles extra over 5 tanks for 7 bucks. I don't know about you, but I can't get 150-200 miles on 7 dollars worth of gas while keeping my fuel system clean. Bascially put, it saves money in the long run.