@wpoll: that's definitely not correct! swirl flaps are not introduced for Euro4 compliance! They where introduced on the Euro3 M57 (yes the old, first generation one) ONLY with the 193 HP M57 and an automatic transmission. The 193 HP manual shift (as well as the 184 HP manual and automatic) never had swirl flaps. The M57 never had a DPF build into by the factory. The DPF was introduced later with the M57TÜ & Euro4 compliance.

According to the ETK: the E53 with the M57TÜ engine will only have swirl flaps if your E53 was shipped with a DPF by the factory. Maybe this little difference (S200A) makes the E53 M57TÜ swirl flaps as rare (depending on the market?) as unicorns

You can easily check if you have the vacuum box (#9) shown here then there are swirl flaps: Intake manifold- Vacuum-controlled | BMW X5 E53 X5 3.0d M57N Europe
If not