"modification" lists up to stage III. I have a Koyo Radiator and love it. If you are upgrading the tubo's and/or turning the boost up then your cooling system should be performing at top notch. Turbo timers are silly, just dont boost your car for the last 2 miles or so before you get out of the car.
Like ZXrider said, pay attention to making sure that your car is in tip top condition before you do any mods.