I was driving on the motorway just now... 5th gear... wanted to overtake a car, but also wanted to have some fun ... so I shifted back to 4th, put my foot down... and then *POP*... something popped and after that the turbo hardly spooled up any more. Also a hissing sound when it's trying to spool up. Dump valve gone? Or just a ripped diaphragm? (don't have tools where I am right now to check it myself but I want to know !)