1995 impreza with EJ20G swap.. so ive been getting this weird noise under load.. starts happening just before getting into boost. it sounds like a metallic rattling/flapping sound, kind of like an exhaust leak would sound. at first i thought it was just that, so i changed out all the exhast gaskets. I thought maybe the uppipe was cracked, cause it seemed to move a little. so i sent off the manifold to grimmspeed to pnp and ordered their uppipe as well. so even after all that the noise is still there. I checked the intake piping, and its all good, no cracks or leaks. its got me stumped