SCRAPING / GRINDING NOISE WHEN ACCERLATING

[DANAMOS11]

Hi everyone. I have a Passat 2004 1.9 tdi AWX 5 speed.
i bought the car 3 weeks ago it was driving perfectly. After 100 miles i was going round a roundabout and i heard a strange scrapping noise (seems like its coming front drivers side UK model). The noise has never gone.
It doesn't happen when stationary in neutral
it doesn't happen when moving with clutch down or in neutral revving the car

It only seems to happen when moving and in gear it starts from about 1500 revs

I have replaced boost pipes as they were leaking
I have replaced Cat as they was leaking from the flexi
I have replaced clutch and flywheel

if i was to describe the sound it sound as if the undertray is dragging on the floor but the car does not have an undertray

I have a feeling this may be a common problem as a Passat past me the other day making the exact same noise