hmmmm not really.... People usually weld up their diffs on drifting cars so they can get the effects of an LSD (both wheels spinning it up) which out having to spend the money. This is not a good idea for a car that will be driven on the streets though... As for welding an STI diff.... why? Maybe you could weld up the center diff to put all the power to the rear all the time, but that would retarded.... Also I am pretty sure that on the newer GR's the cars DCCD would freak the fuck out and cause problems, you might be able to get away with it on the GD's but even then it is chancy. Best idea would be to purchase a new center diff made for the purpose of making it into a RWD. Guy over on IWSTI did it with his GR, only stage 2 but with the RWD layout and all the torque our motors makes he is rocking hard core on the drift courses.