So from what I understand about how the downgrade feature works, It reads the encryption of your nand file and applies it to the gateway.dg and then builds an older nand that it writes to your sysnand. So I have a theory that I want to try but I figured I would post it here first. My buddy upgraded his 3ds to 9.4 on accident. If I were to install a nand mod on his 3ds, dump his nand file then put that and the gateway.dg file on my sd card and then use the downgrade feature, It would write a valid 4.2 nand for his 3ds to my sysnand. If I then dumped that nand using a hardware mod on my 3ds and restored it to his then in theory it would downgrade him to 4.2. After this I could just use my nand mod to restore a valid nand to my 3ds. Does anyone know if this might work? Just a Theory.