Inlet manifold or air-water cooler?

[Alf]

The engine in question is an rb30/25 built to handle 600 hp plus.

The inlet manifold is factory atm.

What do you guys think would be better gains for the $, an aftermarket intake manifold or a aftercooler (air-water cooler) near the throttle body?

The air-water cooler I was looking at was a VORTECH one.

A few of them to choose from:

http://www.capa.com.au/vortech_performance_cooling.htm

Has anyone had any experience with these kind of items?.