The info above is probalby one of the best responses I have seen towards a question,
If you have an SR20 in front, it will hold up, as been mention and in chestikoph rides thread, he has gradually fed power into the stock diff, and got along quite well, and from what i can read does not have an aggressive tune, but I'm unsure how much weight he has over the back,
R31 is almost the same as Commodore live rear ends, unless you are not prepare to throw at least $1200 in the rear end you gonna chew through diffs like tim tams,