Volvo S80 2.4T New TRITDT Compressor Bypass Valve (CBV) repair kit
It felt like the S80 didn't reach peak performance yet and I suspected the diverter valve / compressor bypass valve to be underperforming.
And it seems I was right! It was quite an annoying job to do as space is tight around the turbo.
It only takes 3x 10mm bolts to get the cap loose, but it takes some elbow grease to get to that area.
But it was all worth it. I bought this unit from eBay: www.ebay.com/itm/263368443361