It is another Poke Industries mishmash program in the sense that all it does is allow you to allocate 12, 16 or 20 MB of RDRAM, which in short doesn't actually work unless you modify more of the emulator (in such a way that existing N64 ROMs will no longer run) and make software from scratch for it.
This was originally made for Super Mario 64 hacks with custom scripts that did not fit in 8 MB of RAM, but as I mentioned, it doesn't work unless you properly modify the emulator and rewrite the game from scratch. Which in turn is pointless since you could just rewrite it (or rather make a imitation) for PC instead and bypass all of the N64's limitations.
Tl;dr: This program does not, and cannot do anything different from Project64 2.1 except wasting between 4 and 12 MB of your system's RAM.
Oh, and he didn't release the source code of his modification, meaning he is violating the emulator's license.