If he had an Evo, it was probably AMS Performance.
http://amsperformance.com/
A lot of Evo guys go with their intercoolers. Proven results. Another option is ETS. I plan on using one of their cores when I'm ready for my swap.
http://www.extremeturbosystems.com/
They both use different cores, and are available in different sizes and end tank designs. Check them out!