there's no point in downgrading from 4.3U to 4.1U....just as there's no point in upgrading from 4.1U or 4.2U to 4.3U.....
you just need to run the Hackmii installer (using a game based exploit since you're on 4.3U) to install Bootmii and HBC. then install cIOS236 using the installer in HBC. then use MMM to install your other cIOS and forwarder wads....it's really that easy. ....oh, then install priiloader, enable priiloader hacks, and make a bootmii NAND backup for safe keeping....