I have been researching intakes for my 98 impreza 2.5rs. I have come across some mixed info about them. On imprezars.com, they have an intake that comes from the chamber, and out into the open engine bay (not eliminating the chamber that feeds directly into the throttlebodies). Here is info from there site on this: The features that distinguish this intake over the others is that (1) The intake retains the stock torque chamber at the back of the motor for good low end throttle response, and (2) with intakes going directly to the throtle body, the MAF can be confused by the intake pulse harmonics into reading up to 26% lean, and this kills power and potentially harms the motor over time (see March 2000 Issue of Sport Compact Car Magazine). The other intakes require a $400 super air flow convertor like the APEXi or Field AFC to correct the MAF signal output and this one doesn't. Now later on their site, they have an intake that eliminates that box and they state nothing about this. I was originally planning on buying the Injen Race Division intake until i read this. Here is a link to what i was talking about: http://www.imprezars.com/intake97_99.htm#9798conefilter

Does anyone have any info about this?

thanks in advance for any replies,
luke

 

Well maybe I can provide a little bit of clarity here:

First off any data published about the MAF in regards to the 98-99 Impreza has to be culminated while also taking into account the fact that 99 MAF sensors were often faulty to begin with, and that this may result in a somewhat skewed interpretation of how the MAF typically responds to an aftermarket "cold air" intake, as this unfortunate instance with the 99s has kind of contributed to an unsubstantiated stigma of the often deemed "fragile" MAF sensor. In actuality a well working MAF does provide a great deal of flexibility in regard to the engine and computer's overall ability to adapt to a greater mass of air more rapidly entering the intake tract. The most important fact to note, and to dispel common misperception is that the 1998 impreza MAF is a VERY reliable and versatile sensor. Finally remember that the factory intake is a "cold air" intake, and the only benefit of an aftermarket intake is a slightly less restricted, freer flowing channel for the path of incoming air, and it does not lead to a denser charge of oxygen molecules flowing into the intake tract as one might hope to believe, and thus in a naturally aspirated application the benefits are minimal...