These are some rather important chest to make note of. If you want to have everything best to check these places I missed earlier
- -Mushroom Rock Road: Back at the elevator there's a chest containing the Machina Booster Key Item. To give Rikku's ultimate Dressphere Machina Maw its last few abilities.
- -Mi'Hen Highroad Only accessible via chocobo. You need to stand at the very edge of the cliff and wait there. When the option appears jump down. The Victor Primoris is for Paine's ultimate dressphere's last few abilities.