Audi TT boost?

[Festively Jolly]

hey lads.  ive been playing the game Gran Turismo 3 on PlayStation2.  I
got the TT and the S4 (only Audis to appear in the game as they reduced
the # of cars to about 120 rather than 500 as in Gran Turismo 2.  it had
about 7 Audis.)  Anyhoo, My TT is modded fully with stage 3  turbo
etc... and 406 bhp.  well the boost on it rockets to 2.0 bar at low rpm.
then as it reaches the redline, the boost gets really low.  so as the
redline rises, the boosts lowers?  is this what it is like in real TTs?
this IS the most accurate driving simulator ever. every car has its own
handling quirks and all cars are individually tested.  all other cars,
such as my S4 (609 bhp),  when put to the floor,  the boost maxes and
stays all the way up through the rpm.  is the TT boost correct?