Hey This is a guide how to downgrade from 6.0 to 5.X You need to have SHSH blobs for this and a PC or Mac computer.
First you need to download redsn0w 0.9.14b2 for windows or mac(links are at the end)
Next you need to download you SHSH from TinyUmbrella and you need the firmware corresponding to your SHSH blob.
After you completed downloading you need to "Stitch" The SHSH blob to the firmware(redsn0w>Extras> SHSHBlobs> Stitch)
Chose the IPSW and SHSH then after its done stitching you will have a .ipsw file in the same directory
After That you have to put your devices in Pwned DFU mode (Redsn0w>Extras>Pwned DFU)
The your device is in PWNED DFU so Close redsn0w then itunes will open
Click The ALT key on MAC and the SHIFT key on PC while clicking restore.
Chose the stitched IPSW file and let it restore
******YOU MAY HAVE ERROR -1 or ERROR 1 IF THIS HAPPENS OPEN TINY UMBRELLA AND CLICK FIX RECOVERY********