I've seen many people ask how to do it, and I still can't imagine why anybody thinks it makes a difference, but the idea of how to do it just popped up in my head and it's really simple. You just have to go about it in a roundabout way. 1) Launch the GW menu and create a fresh NAND backup 2) Remove SD card and copy everything to your PC 3) Launch the GW menu again and format emunand 4) Reboot the system and format SYSNAND through system settings 5) Launch GW menu and make another NAND dump 6) Put SD card back in the computer and either rename the NAND.BIN that's on the SD card, or move it to a different folder than the original. 7) use emunand tool to inject this new NAND.bin onto the SD card 8) Copy all original SD card files, including the original NAND.bin back onto the SD card. 9) Replace SD card in 3DS and Launch the GW menu 10) Navigate to the downgrade function and hold UP on the D pad when you press A, to flash the original NAND.bin back. You now have your original sysnand, with original files and progress on your SD card, while having an unlinked emunand. From there, you can follow other guides to update emunand to a version of your choosing. Again... I still don't understand why anyone would think it needs to be done this way (perhaps because of GBA/DSi stuff, but PastaCFW+eshop spoof takes care of that (you can re-download after formatting sysnand)), but there you go.