Have you checked the filter in the airbox?
It could be an exhaust leak on the downpipe area too
I didn't check the air filter, will do that next time. Good idea on the downpipe, I removed some nuts few months ago, maybe I messed up with something.
Is your car still running the original (plastic) dump valve?
Are the hoses to it/from it all attached tightly? A leak there could cause some noise.
Yes, it's the original valve, the hose are tight, one is less tight but it has always been like that.
I was wondering if a faulty dump valve or wastegate could be the cause of the noise ?