1. Someone posted here that they are on eBay but the person is no longer welcome here and besides, it's cheaper from the dealer and are in stock. It's best to buy it from your local dealer instead of one of the internet parts places (Tasca is the best) because the package trips "size rates" from UPS and Fedex and probably exceeds what the price differential is from the local dealer. Check both.
No affiliation I've already got a spare so I don't need it but it seems like a pretty good price ,if someone needs one brand new.https://www.ebay.com/itm/176523198110?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=KD5QwEWsRWK&sssrc=4429486&ssuid=3yiknIEHQOa&var=&widget_ver=artemis&media=SMS
www.fordgtforum.com
But why? Unless it is broken and not just scuffed, you're going to scuff up a new one too. Same applies to the rear diffusers. And chances are you'll never compete in a concourse show.
3. Dealer If you only have one key it has to be programmed by the dealer. My dealer had to order them (and that was 12 years ago) so call in advance. Give them your VIN because when you say "Ford GT" they hear "Mustang GT" and it's not interchangeable.
4. The Borla exhaust (formerly the Ford Racing exhaust) is still made by Borla. Other combinations of X and H pipes are discussed at great length here. Search can be your friend.
5. Bridgestones. You really should read old topics. Tires and batteries are the most common topics and there are many. Search can be your friend. Also, you should probably just get a new battery, Optima Group 25 red top from Auto Zone, etc. The Ford battery is just an optima with a Ford label. Literally. Someone sells labels although if you care you can carefully transfer the old one. It doesn't matter since it's buried under the Frunk liner anyway.
6. Monitor eBay. The reality is that the people here are hoarders
but represent maybe 10% of the total Ford GT owners so you're unlikely to find one here. But stuff like that shows up on eBay. Similarly, if you are in any way a do it yourself-er you should try to acquire the (no longer in print) CD service manual from Helm, Inc. (Print copies are even rarer).
Edit: I was looking at Helm for another reason (just thought of something) and they have the "Owners manual" for $50. I don't know if it's just the book or if it is in the original case. If you need it for reference and not originality try here:
PS. You should contact "dbk" by PM to get your status updated to owner. Then post pics of your car!
Enjoy the car! It's a great driver plus will rip up a track like no other. Be careful though, lots of power and if you still have the ancient Goodyear hockey pucks sudden acceleration in a straight line or almost any acceleration when NOT going straight can cause the rear end to break loose.