Depends on your other mods if any and your ultimate power goal.
Generally e85 can provide 20-30% more power at the same boost level, but that's no good if say you're already at the limit of stock injectors or eg pump.
Iirc on the stock setup, the addition of upgrade pump and fpr running higher base pressure can support stock injectors at around 15psi.
Once you go a bigger turbo or higher psi, then id1000's are a good addition.
If matt has sorted virtual flex fuel for your ECU then that's a start, otherwise you may get an e85 specific tune or require the addition of an ethanol sensor and other mods for a flex fuel tune.
It's something I'm researching, so in for clarification re Gen4 & 5...
It's a good thing either for moar headroom or for engine decarbonising pre oil changes