I have some amazing news to share with you. You can now run iOS 6 on an iOS 7 or 9 Device. I am not sure if iOS 8 is supported.
You should back up your device, because if something goes wrong, you can restore
This works for iPhone 4, 5, iPad 2, iPad 3, and iPad 4 running a jailbreak on any iOS 7 or 9 Version. More devices will be added
Make sure you have at least 6-8 gigs available to install iOS 6
1. Make sure passcode is off until the install is complete
2. Go to cydia, sources, edit, add and type in coolbooter.com
3. You can search for coolbooter, and install and confirm it.
The coolbooter app should be on your homescreen
4. Go to app switcher, and kill all apps in the background
5. Open coolbooter, and click install
You will be presented with a screen that will allow you to select which version of iOS 6 you want.
After that it will ask you if you want iOS 6 jailbroken or not.
Then it will ask you if you want verbose boot displayed. It doesn't matter what you choose, but I would choose no because it is not benifiting us blind folks
6. Make sure your device is unplugged before installing
7. wait for the IPSW to download
8. If you get a message that your storage is almost full, dismiss it.
9. Reboot your device after
10. Go back to coolboot, an click boot
11. It will tell you to lock your device for 10 seconds and unlock
12. The process will begin
If voiceover is unresponsive after you unlock, don't worry
Wait about 2 minutes, and you should be brought to your set up screen
You have successfully installed iOS 6!
If you have any questions, drop a comment.