TD6, when revving my car makes a sort of whooshing sound, which continues whilst it's revving back down. If you listen carefully you can hear it.

I read on the forum that a noise on the overrun is normal on the TD6, just want assurance my sounds normal really  

Got to say that woosh sounds similar to mine and its running fine so that's 2 cars that have the same characteristics. I must admit when I first got the car I thought it might be a symptom of an ageing Turbo. 2007 TDV8 VSE
2003 TD6 gone.
2002 P38a gone
1999 P38a gone
1997 p38a gone
1993 VSE gone
1992 VSE gone
1966 Series 2a with V8 conversion gone

My TDV8 sounds somewhat similar from cold start but goes when the fan coupler has warmed slightly (about 200m or so).

Maybe it's a faulty cooling fan...