You looking for a whole stand alone engine management system where you plug in a lap top and you can change things around? There are many different kind. Check the ECU forum.
There are also piggy back computers that control just fuel delivery. And example of this will be the Apexi SAFC. There is no way we can tell you what kind of computer you need unless we know what kind of mods you have, or plan of having in the near future. Also, we need to know what you plan on getting out of the car? If its a daily driver, you don't need to spend the money on a new computer. If you drag race or autocross or something, you need to explore the different types of computers, what they offer, and decide what is the best one for your applicaton.
Now why the **** do I have to press 1 for English?