turbo in the 09 s60 is dead silent. one thing I'll note is that it doesn't have a wastegate that bleeds into the engine bay. Rather, it has a control valve that bypasses the turbo into its own manifold - so all of the atmosphere in motion is contained within the plumbing. You can barely perceive a "wooosh" sound, not a whine, but a woosh of air circulating when you really dig in. But if you have any other sounds, such as the HVAC, or even NPR, it's masked. 261hp and 258 ft/lbs from 2100 rpm. Not shabby. OTOH, for some reason the 2009 gets really poor MPG by s60 standards, different from the other years.