Well, that's a hard question to answer since there is so much you can do with a UTEC. You can tune it close to stock and see almost no gains. You can tune it conservatively and loose power, or you can tune it aggressively and make power. And, how aggressifely you tune it will determine how much power you will make. And, all cars are different. My car on 18 psi will make a different amount of power than your car on 18 psi (with all other mods being equal). Likewise, all cars can't run the same map safely.
You do need at minimum an EGT gauge to tune it properly. However, a wideband O2 sensor in conjunction with an EGT gauge is the best way to go.
There is no way to say how much it will improve your ¼ mile times. There are so many other factors to consider - driver skill, air temperature, traction, the condition of your clutch, etc. In fact, my car has run as much as a half second different going from a cool day to a warm day.