CHR Jerking Acceleration Whistling Noise

Sounds like a boost leak somewhere. The whistling and hissing, along with the reduced power, definitely points in that direction. Have you checked the cable and plug connection of the boost pressure sensor itself? A faulty connection there can cause all sorts of weird issues. Is the hissing sound coming from the intake manifold or maybe near the turbocharger?

Thanks for the quick reply! I did a quick visual inspection of the sensor cable and plug, but didn't see anything obvious. Is there a way to test the sensor or the connection more thoroughly without specialized tools?

Without proper diagnostic tools, it's tough to pinpoint the exact cause. Given the symptoms and your mileage, a failing boost pressure sensor or a leak in the intake system is highly probable. Considering everything, and to prevent further damage, I'd recommend taking it to a workshop for a proper diagnosis. Could be a simple fix, but better safe than sorry.

Thanks for the advice. I took it to a local workshop, and they confirmed it was indeed a defective connection at the boost pressure sensor. Repair cost me 95€. Runs like new again!