I went Stage 1 at around 80k and it was fine... I went stage 2 around 120k and it slipped a bit, but it drove ok if you didn't boot it from low revs. This was on a spikey " off the shelf " map though, there are much better linear custom maps from the likes of rtech that will give you all the power and torque but not in a fashion to destroy the clutch and tyres.
As you rightly point out, it varies wildy