With what you have so far on your '18 3.5L, this XDI-EVO would be the best step forward IF you have access to E85. If you're limited to 93 octane, then consider water/methanol injection and/or upgraded turbos.
AEM V3 1.15 Gallon Water Injection Kit https://www.morepowertuning.com/aem-30-3300
Garrett PowerMax Stage 2 Turbo Upgrade https://www.morepowertuning.com/grt-2017-up-35-stage2-turbos