It'd probably take me a couple days to break one, depending on what shape the clutch and motor are in.how breakable is it?
Yes. Any use induces wear. However, ideally the gearbox will outlast the motor and at least two clutch assemblies (but this doesn't mean people don't have failures within months either).will doing that reguarly wear on the tranny?
It's not as dependent on the gearbox as it is on the user sometimes; other times it's purely mechanical. That's why experiences will vary and why it is highly unlikely a definitive answer will result from this thread or any thread like it IMO.also can a stock tranny handle the cobb stage 2?
Have a look at the links in my signature, there's lots of threads with info you may find interesting. Welcome again!