CNC ported cylinder heads with 1mm bigger valves, different cam profiles, short runner intake manifold. Forged internals help keep her together to the 7,500 redline.
there is lots of media coverage on the subject. I believe I found a good article from one of the mustang magazines, but I can't find the link now. Sorry.
Pick up the August issue of 5.0 Magazine. They have a huge break down of EVERY part of the Boss 302 engine. It will answer all your questions, with pictures of EVERY part too!