hi i have a mark 4 golf gt tdi, the problem is that the diesel engine sounds like and old ford transit, and the turbo seens too start a loud whistle at about 1500rpm, now i am not much of a car or vw expert and is the first golf tdi that ive had. but have previously had a vectra tdi tht wasnt as loud as this, my friend also has the same car as me but is alot quieter, i suspect that there may be a leak in the turbo pipe or a exhaust that may have blown or even something to do with the exhaust manfiold, but dont know how to check these faults to confirm. Can anyone tell me of what i can do to resolve this noisy engine, any tips or advice is appreciated.

thanks

Jeff