I just wanted to give everyone my experience with a K&N dropin filter. I recently purchased a 350z and plan on keeping the original filter.

My previous vehicle was a 2001 Nissan Pathfinder. I had been using the K&N Drop In with no issues what so ever. Recently my gf bought a 2003 QX4, same engine as the Pathfinder. I purchased another K&N Drop In for the QX4. About a week later the engine began having MAJOR rpm problems to the point where it would not go above 3k. After bringing in the QX4 to Infiniti and a Mass Air Flow Sensor replacement everything worked fine. Infiniti claimed that the Mass Air Flow Sensor had been damaged due to contamination by the oil from the K&N drop in. The dealer considered this an "out-of-warranty repair" so we were charged for the replacement of the sensor. After several months of discussion K&N covered the cost of the repair. I sent over the Mass Air Flow Sensor as well as the Drop In Filter. 3rd party testing results should be available shortly and I'll let you all know how it went.

Because the QX4 and Pathfinder have similar 3.5L engines I'm assuming that the Mass Air Flow Sensors are similar if not identical therefore I am extremely hesitant to put a drop-in into my new 350z. In addition to possible issues I have read several threads that question the claim of any performance (HP) or fuel mileage improvements by using the K&N Drop In.

 

I have had mine in for 7,500 miles and no problems. Don't forget to stick on the foam spacer thing that comes with the filter. It's stuck up inside the box.

 

Over oiling the filter can cause MAF failure especially the screen type MAFs from Bosch. Most latter MAF designs from Japan tend to deal with hot wire fouling a lot better. I run a K&N for pressure drop advantage over a stock paper and don't expect any power increase, but do expect a crisper throttle response which seems evident via butt dyno.

 

Used the rubber spacers
The filter was brand new in sealed plastic baggie before i installed it.

 

They're have been reports of over oiling from the factory causing MAF failures in other types of cars as well. Blotting the filter with paper towels prior to install seems to be an acceptable precaution with good results.

 

I have one in my G35C with no issues. It's been since day one.

Lou

 

Do the claims by K&N regarding performance increases (HP) and better fuel economy have any merit in your experiences?