There is a unique K&N Filtercharger replacement element for all Honda models that they cover and in the catalog, there are almost 120 pages that lists all K&N Filterchargers made, Honda models covered will include all variants that have been marketed in the United States. Obviously JDM and non-US models will not be listed. However I was using a K&N in my previous Malaysian market EF-Civic 1.6EX which uses a 1590cc SOHC dual Keihin carb'ed engine and the K&N Filtercharger I got was listed as for the 1.4l dual-carb'ed European model so it would seem K&N do make Filterchargers for non-US models, perhaps in their manufacturing facilities outside of the U.S.

There is also a Honda OEM filter part-number to K&N Filtercharger model number cross reference in the catalog and this cross reference table would probably be more useful to owners of JDM and non-US spec Hondas. The table is reproduced on the right but at any time, K&N should still be consulted for the latest correct cross-reference list.

The strength of K&N Filtercharger replacement filters is that they can be directly installed in place of the original filter. No fitting of any form is required and because they work with the stock air-intake system, enjoys almost the same low noise level as the stock OEM filters but with higher air-flow and longer service interval benefits.

Fuel Injection Performance Kits or FIPK for short are the famous K&N open-element cone type filters. Designed to be used with fuel-injected engines, FIPK replaces part of the stock air-intake system, typically the air-box that contains the filter element. Installation of FIPK will require some fitting and mounting work; first the stock air-box will have to be dismantled and removed from the engine bay, then the FIPK kit will have to be installed in its place.

In most cases, the FIPK will contain all the parts needed to make the filter work, including (if necessary) a pipe to insert into the stock intake hose so that the K&N cone element can be placed in the area where the stock air box used to be.

In the catalog, the K&N FIPK Design Concept is explained as being to promote performance in fuel-injected stock engines by creating air filtration with the least resistance in air-flow. FIPK's have specially designed filters with woven cotton fabric pressed between 2 layers of wire mesh screen (ie the element design described above). The screen and fabric combination is said to create a grid-like effect which actually straightens out the incoming air as it passes through the filter. FIPK's also have uniquely designed adapters that act like a built-in velocity stack. A velocity stack is a specially designed tube that has varying diameter, typically larger at the mouth and gradually tapering smaller. This design is supposed to increase the velocity of the air as it passes through the tube and thus contributing to better engine power.

The velocity stack creates a radius entry into the mass air sensor reducing restriction and allowing the engine to pull in more air. Note this point is not valid for Hondas because we use MAP air sensors which uses air pressure to measure air flow velocity. MAP sensors do not produce any restriction to air-flow unlike mass air sensors.

K&N have also started marketing their FIPK generation 2. The main feature of FIPK-2 is the use of an extra screen to shield the K&N cone from the rest of the engine bay and thus providing the so-called cold-air intake effect. However, at the time of writing of this article, K&N does not produce FIPK-2 for any Honda models. A picture of an FIPK-2 for a US make is produced on the right.

Like Filtercharger replacement filters, K&N produces a specific FIPK for each Honda model they support. The main Honda models K&N supports includes most versions of the Integra and NSX (marketed as Acuras in the U.S.) and the Honda Civic (and CRX).