The turbo questions have been answered well here, so I will contribute to the methanol inj. Ideal, 100% methanol will supply not only the cooling of a 50/50 mix, but it also works as a supplemental fuel delivery allowing greater boost without fear of going lean (if the HPDI pump and injectors reach capacity). This may require a meth system that can work with 100% methanol, and it requires nozzel sizing smaller than the water/meth mix as well as boost controlled activation that is graduated....but is an excellent upgrade. Using 50/50 mix just cools and does not add usable fuel as the water portion negates this.
Also be aware that you can only ingest so much water before it will also cause spark blow-out similar to a too large of plug gap.
On the GM LLT DI v6's, we had to add 100% meth when we exceeded 400 or so at the rear wheels as the LLT fueling would run out around there. The 2012 and up LFX allows us to reach close to 500 w/out issue.
There is one person in the industry I hold in high regard, Julieo from Alky Control that has several white papers to read about all of this explained in detail like I do on PCV systems for those wanting to research more.