I replaced mine this afternoon, after getting the feeling the car didn't feel as sharp as it has been, tiny bit flat, but not think anything was majorly wrong.
I have never removed my diverter valve completely in 55k miles, removed it today to find a 5-6mm well worn split in the diapragm ,which has turned into a hole !!!
I've always had a warning in vcds about my emissions control light bring up an error of Bank 1 lean. implausible signal below threshold warning, which I've always thought I had a possible faulty lambda sensor, which I was gonna change to try fix it.I never really thought much of it. so just left it be. It's been like this for at a guess, nearly a year.
replaced the Diverter valve today, with again the thanks to Mr vRStu having a spare new diverter valve in his toolbox, as the dealers didn't have any in stock as per usual.
Car now, although always was fast, is now a complete animal !! So much smoother, dam quick, has also improved my cruising mpg by at least 3-4mpg.Car even starts better, and less lumpy.
My error on vcds has now also cured. So must of been low boost that was causing implausible readings at the Pre cat lambda sensor.