If running high boost I would say water injection.
Only because you keep the charge temps low (like an intercooler) and you also get some extra protection against detonation (unlike an intercooler).
Plus WI costs much less than a good (large!!) intercooler.

I am going running both on my car (when i finish it), but that is only because I need it to show my WI kits rather than needing it. I only will run 10psi boost on an 8.5 : 1 comp ratio, so a good intercooler is all I really need.


Darren