The Hayabusa armor in Halo3 is a nice visual change you can unlock to change the default Mark IV armor that your Spartan wears. See the picture on the right for a screenshot of RedDeath in the Hayabusa armor. Unlocking it requires a few hours of work, you need to locate the all the hidden silver and gold skulls that are spread throughout the campaign. I spent quite a bit of time online figuring out how to get this unlocked and I've aggregated this information in this post, I hope you find it useful!
All the skull locations are detailed well at Halo3Planet. There are some gotchas that you need to be aware of:
1. You need to run the game in Normal or higher difficulty, you cannot do this in easy mode.
2. You need to start at the beginning of every level. If you've already played the campaign, then it's easier so you can skip to the appropriate levels to pick up the skulls.
3. You can exit the level once you pick up the skull, you do not need to play it all the way through.
4. You do not always unlock an achievement for picking up a skull. For example, the first skull does not give you any indication that you have unlocked it when you pick it up, other than the fact that you are now holding a skull. If you want to see the skulls you've unlocked, go to the settings panel just before you start a campaign.
5. The IWHBYD (aka I Would Have Been Your Daddy) skull, which is the last skull you need to get, requires you to jump through the halo rings in the following order 1 3 4 6 7 5 4 6 5 4 5 3 4. You do not have to do the extended version of this permutation that some websites have posted. Also, if you screw up in between and accidentally jump through a wrong sequence, just start again at the beginning.
6. If you don't understand where the skulls are located after reading the directions at Halo3Planet, I found it useful to watch a video of how to get at the skulls on YouTube. All the skulls have a video of how to get to them. There is also a larger video clip at http://www.gamevideos.com/video/id/15032 that has the location of all the skulls.
If you face any issues when trying to get the skulls that this post didn't address, please post your question (or your solution) in the comments and I'll update the post. If this post helped you, please do let me know by posting a comment.
