A lot depends on how you drive it, but I guess it isnt far wrong saying they are on par with an MT75.

Ive seen cars survive with 400bhp on a standard box, and others destroy one in very swiftly with a little over standard.
I broke my old Legacy box one night.....although sidestepping the clutch at 7000rpm in 1st gear....well, I guess I shouldnt have expected otherwise

It was wet though lol

Usually power munches 3rd gear. STI style boxes are stronger than earlier ones. the casing was beefed up a bit, and I think the bearings inside. Gears...paople say theya re the same, but they do seem to withstand a little more power.

As for the shaft Johnny mentioned. Ive never seen or heard of thet problem before, and Ive been around hundreds of Subarus.
I can only assume that problem is a result of idiots changing the clutch. As the shaft is located in place and secured by a large threaded plug, which is usually very tight. Almost impossible for it to come out under normal operation, more so as its right beside the starter motor.


If your friend is upgrading the power to that level, and is concerned about the box....cheapest strong solution is to throw a new model 6 speed in there, It will take 500bhp no problem.

PPG's are strong, and expensive.....but every race meet I hear of, some break.