Their good enough to use in the Skyline RB25det'd applications... (same gearset, different case) and lots of folks putting serious HP thru them
Matter of fact, how many guys with high mod Z32TT's using the stock trans, have broke them? I haven't heard of any... so in short, from what I know of them, they are pretty stout.
So much so, that I bought one to put behind my RB26dett that will be putting out some pretty nasty power soon...