I have no idea what you mean by "so basically theres no performance needed with the brakes?"
Subtle hint was missed: what is your current setup? Since it's a 90-91 coupe (I can guess that from the pic), I can't tell whether you have drums or discs in the back -- some GTs came with rear discs.
Brake squeal isn't the result of small brakes. It's either a lack of proper lubrication of the sliders (caliper could be seized), lack of grease on the shoe sliding points, insufficient shims (some models use three on the front caliper, four on the back), failure to apply brake grease to the inner (piston-side) shims on front or rears, missing pad supports or worn out friction material on pads or shoes.
http://www.celicatech.com/imagearchive/bgb...ch/BRAKE_S2.PDFIf you've got everything properly greased and installed and your rotors and pads are in good condition, you shouldn't be getting a lot of noise. If you are, try upgrading your pads for noise suppression.