http://www.sn95brakes.com/sn95brakes.php
Brakes - Cobra Big Brake Kits
http://www.mustangtuning.com/mustang-brake-conversion-kits.html
Performance Parts | Suspension Parts
'99+ V6 & GT: 10.8x1.0" front rotors, 44.5x44.5mm dual piston PBR calipers. Rear single piston Varga caliper, 10" solid rotor
'99+ Cobra: 13.0x1.1" Brembo rotors, spec'd 40x40 mm dual piston PBR calipers. Rear single piston 38mm Varga Caliper, 11.65" vented rotor
'00 Bullitt Mustang: Same brakes as 94-98 Cobras (unique red PBR calipers with running horse up front, same varga caliper in rear painted red.) Rear single piston 38mm Varga Caliper, 11.65" vented rotor
Use Cobra rotors front, cobra rotors rear, rear axle bracket & anti-moan brkt different than GT. You want stainless braided hoses at front - watch which thread pitch you get to make sure they fit the specific calipers you buy. Is the Summit kit the 10th Anniversary red caliper set? If not, post link? Don't believe the Cobra rear caliper is different than the GT; pads may be thinner to accomodate thicker Cobra rotor. Cobra/Bullitt/Mach I rear rotor larger diameter than GT.
Picking my '01 GT up Sat. a.m. after install of complete 10th Anniversary Cobra caliper kit. Using Baer Eradispeed+1 13" rotors on rear which does not need axle brkt or moan brace change. Front is the Cobra caliper set, braided hoses, and Baer Cobra rotors that are drilled to match rears. Pic is my 96 GT with the Baer F/R.