Straight denatured, straight methanol, or isopropyl. Those are the three types of alcohol.
Xylene is a solvent, unlike alcohol. And may be aggressive on plastics.. so careful. Do not use. Just like MEK, acetone, muriatic acid, ether, hydrogen peroxide, nitromethane, etc.. watch out
If you want to run low boost and mix.. thats ok. mix=water/alcohol.
Typically 50/50 or greater content of alcohol. I run straight methanol. And depends on pump being used. If your system has an EFI type pump, then a lube is needed to be added to the alky. To lubricate the rollers inside the pump. If you have a diaphram type pump, none is needed as the internals are plastic.
The Shurflo is a diaphram pump.
SMC uses an EFI style pump. Thats denatured and klotz lube is recommended.
HTH