also I've ordered the 20G wheel, machined Evo III compressor housing and genuine MHI rebuild kit from kando-dynamic aka kinugawa turbo and found their service very quick, however the Evo III compressor housing is obviously a copy, but the quality looks to be just as good as the original compressor housing. I am unsure of the origin of the compressor wheel, but I assume it isn't genuine MHI.
As my original VR-4 turbo is a 'big 16G' using the 'super back' style wheel, the 20G wheel simply swapped in place. You will not be able to fit a 20G (or even a big 16G wheel) on a 14B turbo core/cartridge, UNLESS you machine out the core to suit the larger diameter/shape of the underside of the big 16G/20G wheels. I am not sure about the small 16G which is why I haven't mentioned it yet - to be honest I don't think I've ever seen a small 16G turbo, all the Evolution VR-4s, Lancer Evo1/2/3 I have come across have big 16G turbos. I think perhaps the small 16G is an American thing rather than on JDM vehicles. I would have assumed being a 16G they too would be a 'super back' wheel, but those links above are suggesting otherwise.