Hi All, I have a BFB engine in a 1.8t Quattro that's just had a new turbo, cat fitted. Over the last few days I hear a Leak on acceleration from the exhaust. If I rev the engine slowly there is no noise but if I rev it hard there sounds like a leak in the exhaust. The noise goes away when the engine stops rocking with the power at about 4k and isn't there when the revs drop. I thought it was a leak at the flexi pipe but it sounds further up and if I get someone to rev it I can't feel any leak at any of the joins. Any Ideas anyone on what to check next?