CAI for Fiesta ST
While I'm not sure I believe in performance gains, when installing on the ST Fiesta the sound gain is amazing! Be warned though, until you can delete the Symposer the cabin is rather loud with lots of whooshing and turbo blow back noise. Which are completely different noises than you hear when you just open all of the windows.
Most outstanding intake in the market
The injen SP9015 cold air intake enhances both torque and horsepower in full rpm range. Some of other vendor's CAI will go along with side effect(torque lost in low rpm), but this issue didn't occur on Injen's cold air intake. Therefore, I think that the injen SP9015 cold air intake is the most outstanding intake in the market.