On the E85 and timing corrections, United use different base fuel for the 15% , they state its 'premium 98 or regular petrol' with the rip off approach at the moment I am very sure its regular petrol now. Plus E85 and other E level mixes require you to run an anti gum additive now and then too. I use fuel doctor. Over time you can wind up with black goo in injectors and things.
Nulon pro strength is a good booster NF is even better if you wanted to add to E85 (very low amounts needed 1ml per litre )
https://nitrous.com.au/