Of late I have noticed a slight increase in noise when the exhaust is cold (1st thing in the morning). I get a little more whistle and can hear the solenoid and turbo working, until things have warmed up. I initialy thought it was blowing but further inspection has found, that I think the downpipe wrap/lagging has gone hard and may even be stuck to the pipe.
It's certainly not as soft as the wrap I have on the centre section.

Come to think of it the sound appears to be fairly similar, although not as pronounced, to when I had the downpipe naked/un-wrapped.

I seem to remember others quoting that theirs had deteriorated over time. If so did you notice the noise increase mentioned above.

 

SHOULD GO LIKE GLASS