Actually 98% althouh it sounds great is by OEM industry standards a VERY POOR filter that lets about 10 tims the amount of dirt into an engine compared to OEM filters which generally will be 99 to 99.7% effective. A K&N filter is rated at 97% effective.
Below is a copy of a report from the Duramax ISO airfilter test.
Quote:
In 60 minutes the AC Filter accumulated 574gms of dirt and passed only 0.4gms. After only 24 minutes the K&N had accumulated 221gms of dirt but passed 7.0gms. Compared to the AC, the K&N “plugged up” nearly 3 times faster, passed 18 times more dirt and captured 37% less dirt. See the data tables for a complete summary of these comparisons.
So these filters should not be used unless you are doing real short duration oil changes in the range of 2,000 to 3,000 miles max, which would make running synthetic oil as required by warranty very expensive. If you use these filters you might as well switch to a non-synthetic oil and do 2,000/3,000 mile oil changes. I have talked with people that used these filters for years with no ill effect, but they were doing 2,000/3,000 mile oil changes compared to our 6,500 to 12,500 mile changes. This will make oil changes more expensive then using synthetic oil, requires a lot more down time and negates any MPG gain. As the mfg or user stated there was no HP increase on the dyno, so there is no real gain or reason to use the system other then to look "cool" and be thought of as uninformed by most of the experienced pro's who do not use these filters on their OEM cars at home.
One needs to remember that these filters originaly came about for use on race track and off road race cources and were used on vehicles that were torn down and rebuilt after races or on races like the Baha 1000 or such as the Dakar where they even have an oil change durring the race while drivers rest. These filters were then brought to the street use by some of the uninformed and the company's like K&N came about for this very lucertive money making market.
There are a couple of old sayings that come to mind here "Buyer beware & Afool and their money are soon parted" when I think of all these aftermarket filters that people buy due to marketing sales hype.