In 2004 Volvo introduced the R exhaust manifold for the S60R and V70R which were the high output models for that platform. This new exhaust manifold design incorporated a better merge of the individual runners along with reduced intrusion into the collector.
In short this manifold provides more laminar flow of the exhaust gasses into the turbo which provides earlier spooling and higher power output when compared to the standard 5 cylinder manifold. Can accept both TD04 and K24 turbochargers without modification.
If you're upgrading your turbo this is a great addition!
*These manifolds are used and in good usable condition*