350lb-ft should be fine on FWD...even with sticky tyres the tyres will spin and protect the clutch to some degree.
People used to reckon the dual mass flywheels were only good for 300 lb-ft before they start to grenade...but this seems to be torque delivery and driving style dependant, as you'd expect.
I was putting 330 lb-ft through 4WD on my S3 and the clutch was standard, and still fine after 4 years and 20,000 miles.
You could make it slip by doing repeated drag type launches...whereas the GTI will just spin its wheels in the same situation.
Diesels seem to give dual mass flywheels and clutches a harder time, presumably due to spikey low down torque delivery...and 320 lb-ft doesn't seem too much of a problem for the clutches on those.
In my view/experience, stage 2/3 on the standard turbo will be fine unless you drive with no mechanical sympathy. For a bigger turbo and bigger torque/power gains, I'd look to upgrade it.
