DI injectors need a cleaner more than regular port injectors as they are subjected to combustion by products.
I am beginning to see more and more DI units come in, they are badly fouled externally with hard carbon on the tips not just the usual internal varnish and other contaminates.
PEA based cleaners work very well in these types of injectors, the sooner you begin using them the better, they are hard to clean once the stuff as built up, its better to prevent it as much as possible.
Using top tier fuel may or may not be of benefit, some companies only put decent amounts of detergents in the high octane fuels, the lower octanes may only meet the minimum.
I like Redline SI-1, it is made for continuous use, a few ounces per tank will go a long way in keeping them in good shape.
Whether or not PEA helps the back of the intake valves is still being debated.