Many are running the GT28R/GT2560 already. The inlet difference they're referring to is obvious in the respective pictures of the turbos, 2554 = hose clamp inlet and 2560R = 2-bolt flange inlet (like the stock turbos, but different spacing and clocking).
Again just search for GT28R and you'll find more than enough info to keep you busy for awhile.
________________________________________ NA to TT, starting from the ground up...