Good idea for a thread. I also hope the lack of responses in this thread means there are few problems with this. There's a long thread (269 Posts) about this stickied higher up in the Maintenance sub-forum with no posts for a while, so it will be good to get some updated info. I read that whole thing as an interested prospective owner, and for those who don't have time or patience to read it all, here is what I got from it and a few others as far as the outlook for our cars and good ways to prevent carbon buildup on intake valves:
* Ford has done a good job with ECU programming to minimize the issue. Along with new-generation injectors, it appears that this will let our engines be less plagued by this issue than some earlier GDI engines, especially the Audis, so that if we do have to do a cleaning, it will hopefully be considerably less frequent. There indications that in general intake valve buildup is less of a problem on newer GDI engines.Software updates from Ford may help if available.
* Top Tier gas is helpful, as mentioned above.
* Use high quality full synthetic oil.
* Warm the car up to full operating temperature as much as possible and drive it that way for a while.
* Run it hard sometimes after it's fully warmed up, the Italian tuneup mentioned above. There was some debate about this one because of the injector setup on a GDI engine, but hell, at least it'll be fun, right?
* Catch Can? There was a big difference of opinion here, with some feeling they help, and some arguing they don't and that there is essentially one already built into the system by virtue of a vent hose going to an air/oil separator I believe.