Unfortunately I put my Takeda intake & light pulleys on at the same time so couldn't tell which one made most of the difference, it was noticeable
I chose the Takeda after watching some comparative videos on YouTube.
[ame="https://www.youtube.com/watch?v=VeEpMsKWek0"]2013 Scion FR-S Intake: Takeda Dyno Test - YouTube[/ame]
They compare quite a few others as well.
Here is another one for the S2000
[ame="https://www.youtube.com/watch?v=xwNtjKT_1cA"]Cold Air Intakes Mythbusted [Naturally Aspirated] - YouTube[/ame]