[beepbeep]

There is a vent on the top of the wastegate bell. If you can blow air trough it, wastegate membrane is ruptured and needs to be replaced.

You pegged boost at 1.5 bar? Hmm, is your overboost switch in working order? It's there to prevent exactly that sort of things. It should cut ignition at roughly 1.1 bar.

If you peg your boost at 1.5 bar couple of more times you might need little more than wastegate membrane. You'll need new piston compression rings to begin with (frankly, you might need them already).