How is Honda preventing carbon buildup in its gasoline direct injection (GDI) engines?

I know Toyota/Lexus is using secondary fuel injectors to periodically wash the valves, but how is Honda accounting for carbon deposits in the Fit, Accord, etc? Send links if you have them, not guesses. Thanks.

General problem with GDI:

http://www.thetruthaboutcars.com/2012/05/ask-an-engineer-gdi-problems-in-a-nutshell/

All DI engines have that problem. Despite Honda get in too late in the game of DI engines for some reasons but I've heard that Honda is working on a newer technology to combat carbon build up but if they ever come up with one and better than the present i-VTEC I with better VE of 65:1 and still up with the ponies as well as the longevity then I won't be the only one that happy. (The conventional DI engine VE is 40:1)

Our shops are still using whatever available on the market right now for PM as well as repairing the carbon build up. We have what's called "Walnut" machines at both shops to clean the carbon behind the valves. Worked pretty well in cleaning. The valves looked almost brand new afterward.

I have not searching for any link, but I'm sure there are a few available as well as some threads in some forums. Shall look for when time permit and put into my data base for future references.

Edit: Anybody? Have links, please post so I can learn about the new technology that Honda is doing or is it still a top Honda secret?