Quote Originally Posted by hardwang View Post
That is true. Fuel won't reach the back of the intake valves, therefore there won't be anything to clean it.

The theory behind italian tune up for DI as I recall, is that "supposedly" you run the engine hard long enough so that the engine produces enough heat to melt the carbon deposits off. I'm not entirely convinced that its enough or it even works at all.
ah yes driving 5000rpm for an extended period.. but how for long? maybe get a USB boroscope? see how it looks before and after?