i am thinking of buying a cobra bumper(for my 90 gt), does anyone know how step by step to take out my gt bumper and how to install cobra bumper.... thanks

 

You should check chiltons for a step by step, but it basicly goes as follows:
Get under the car and unbolt the several bolts on the bottom of the bumper cover where it bolts into the radiator support
2. Reach up by the fenders and there should be about 5 or 6 bolts connecting the fender to the bumper, remove these
3. You can now remove the bumper and don't forget to unplug the headlight/foglights