From what I understand, the emergency relief valve is a back-up in case the wastegate on the turbo does not function or gets stuck closed. It is also there so that when you close the thottle at full boost, you don't have an overboost situation in your intake manifold. So basically it bleeds off excess boost. The only symptom that may occur is that you would have excess boost (your boost gage goes into or past the red zone) and your car would have more power. What type of symptoms are you having????