06 M45 K&N Air Filter....

[schu300]

Trying to replace my stock air filter with a K&N or any other brand someone may suggest. Can someone confirm/deny this K&N part number I found to fit 07-08 M45 4.5L, but it says nothing about 06, but I assume being the same body/engine that the air filter would be the same?

Thanks in advance!!

K&N part number is 33-2398http://www.knfilters.com/air_f....aspx

[Q45tech]

The difference in restriction between oem and K&N is less than 1/15 of a percent and results in more small particles geting onto rings causing accelerated wear. But that may only show up after 150k.

Even 10 HP is insignificants [vs weight] so the less than 1 you gain is worthless.

Depends on how long you want to keep engine and whether you care about future owners.

[schu300]

so your telling me that the stock air filter is better for my car (long run) and just as efficient as a K&N Air Filter? I just want to make sure I understand you correctly....

[striz923]

that is how i understood his post. minimal difference it sounds like...

[szh]

The general consensus (but not shared by everybody) is that the gain is relatively imperceptible.

However, the side-effects can be painful. Using oiled air filters means that micro-particles of oil get into the air stream. These tend to coat the MAF sensor over time, leading to poor engine behavior.

The gain is not worth the pain.

Better to stick with the stock OEM air filter and change it regularly (it is inexpensive enough).

Z

[SteveTheTech]

The factory air filters still have a certain amount of oil on them to trap dirt, but they usually do not have enough to damage the MAF. Even at retail it's half the price of a K&N.

I don't think the cost benefit ratio works, but some people like the thought of the extra horsepower even if nominal, I don't get it,but they swear by them though.