Thinking of water injection..any recommendations?

[classicauto]

I believe the smaller, or standard, pump is 130-150psi which is what I'm using at the moment.

They offer a 220 or 240psi pump for multi nozzle setups. That will be the only upgrade I'd do. IMO the higher the pressure the better in these systems with a mechanical pump. Plus taking into account the different losses AND manifold pressure you really don't end up with much pressure at the head of the nozzle.