A little help from a new Skoda Owner

Hello Everyone :-)

I don't know if this the right place but I am new here and in need of some help from some fellow Skoda owners

After owning a Passat 1.9TDi 2002 and it being written off I have now own a 2002 Skoda Octavia 1.9TDi Estate Elegance.

Already I have noticed that I can hear the Turbo whooshing thru all the gears and that I can her the waste-gate releasing all the air when I change gears. (its like having a dump valve its that loud),

Also when accelerating now again the car seems to hesitate and judder then be ok, sometimes it goes into limp mode but again when it does this you can hear the waste-gate dumping all the air. (this seems to be getting more frequent).

Now my guess is either the N75 Valve or Boost sensor, seen as I have a brand new boost sensor from my 2002 1.9TDi Passat left over I guessed I would try that, but for the life of me I cannot located the boost sensor on this car.

A friend of my also came round and checked for boost leaks and he did some tests and said there are no boost leaks.

I hope I have been able to describe this accurately and someone can point me in the right direction.

Many Many Thanks in Advance.

Ashley.