One of the flaws with direct injection engines is that they have no effective way to keep the intake valves clean. Typically on port injection or carbureted systems, the fuel is washed on the valves which helps to prevent gunk from building up, and keeps the valves relatively clean. With direct injection, since the fuel is sprayed directly into the combustion chamber, no fuel touches the back of the valves.
The Ferrari 458 has direct injection and after only 43K miles, my valves were in pretty bad shape! So I ended up cleaning them using walnut blasting. But I decided that I wanted them to stay clean for as long as possible. So I bought 2 Mishimoto Oil Catch cans and installed them on the PCV system. The PCV system will tend to put some oil particulates back into the system so this should help eliminate some of the gunk and build up on the valves.