K&N vs. GReddy
 

I installed the K&N air intake when I bought my BRZ last November. Ever since, I threw periodic P0171 CELs. It would seem that the LTFT was running WAY lean especially when the ambient temperature was below 60. After several correspondences with K&N (they were extremely helpful and sympathetic, I might add), brainstorming with the dealer, and trying several countermeasures, I decided to swap it out with an intake from GReddy last week. Ever since, I've had no CELs. Plus, I think I like the way the engine sounds, more so that than the K&N.