So we have:
methanol injection (proven),
catch can system (variable results),
manual valve cleaning (walnut shell blasting, or soaking/removing, etc),
use of low volatility full synthetic oil,
periodic cleaning of the CAC, and
a minor increase in the fuel's E content
in our DI arsenal.
In addition to running an FI cleaner through the tank periodically or a fuel system treatment, of course. But that applies to pretty much any fuel system, MFI, PFI, DI whathaveyou.