Volvo's V8, known as the B8444S, is an odd duck. Developed during Ford's ownership of the company, both Volvo and FoMoCo swore it wasn't a Ford design. Instead, it's claimed, it was designed in Sweden and built in Japan by Yamaha with a 60-degree bank angle and intended for transverse applications. In stock form, snuggly nested into an XC90 or S80, it made a healthy 311 hp and 325 lb-ft of torque. But it didn't sound like anything special, really. At least, not this special.
Moto Wydech gets credit for uncorking a real ear-turner, fabbing up a custom exhaust for this S80 V8 that makes the staid Volvo sound raw and unhinged. It's not quite a 650-hp Polestar-built V8 Supercars mill, but for a Swedish executive express, it's pretty wild. Volvos of this era go for pennies on their original dollars. The staggering depreciation might be worth it if you can get a shop to fabricate something like this for your S80 or XC90.