You should at bare minimal have a upgraded in tank pump and unless you know exactly what the ethanol content is at every fill up , a flex fuel kit. Ethanol typically varies from 50% to 90%. Unless you live in Arizona where it's restricted to e54. Your tune needs to match the Ethanol %.I have a 2016 WRX with ETS exhaust, pro-tuned for 93 octane. If I want to run E85. Will I have to replace other engine components, or can I just retune? Thanks for reading.