For the brakes- I imagine any good name aftermarket pads and rotors will be a good upgrade. Their are also threads on I think 12" brake upgrade. Just gotta search.
For HUD.
http://www.grandprixforums.net/gemin...ics-20252.html
http://www.grandprixforums.net/addin...3-gp-8171.html
You can upgrade to 04+ gp seats
http://www.grandprixforums.net/seat-...-03-a-279.html
And I don't remember anything about plastics being swapped but you can always paint your plastics.
Both of these are for 97 - 03 gp's. Just do a little more searching and I think you'll find what ya need
