With all the concerns about broken axle shafts on the sti's, I have begun to consider upgrading.

from what I read on driveshaft shops website it seems they feel the cv's are adequate for up to 600whp but the shafts are very brittle and weak.

Anyone have any input or experiences?

I dont plan on ever exceeding 450 or so whp so stage 5's are beyond practical IMO

Yeah I am running the driveshaft shop axles on my 04 WRX its currently pushing 500whp and 515nm of torque with more power in the future. No problems yet...