04-14-2006, 01:20 PM
Any Intake system on the STi simply leans out the car and can produce gains... The K&N Typhoon does this and produces great gains but also seems to provide a lot of heat soak when the car is run hard for any period of time. The main problem seen is people want the cool sounds of the turbo and put a BOV on the car that runs the car rich between shifts. The stock BOV can hold more PSI than the stock turbo can throw at it so that has no need to be changed. As long as it is a high quality/tested intake (K&N, APS), you should have no problem... Issues seen by the leaning out are rough idling and code throwing caused by the changes of flow passed the MAF sensor... this is fixed with engine management (Cobb accessport, TurboXS UTEC). Pretty much anything you do to the car, at least get simple engine management for safety concern. Cobb accessport is like $500.00 and is a simple base engine management system. (simple flash of the ECU by a handheld device with pre-tuned maps). Pretty much point being, the stock system was designed fairly well and changing these specific parts does not provide many realistic gains. Also it changes the dynamics of the car that the stock ECU does not like and can effect performance negatively if not done properly.
EDIT: Lee beat me to the punch.
EDIT: Lee beat me to the punch.