You don't say what engine you have. Regardless, don't go K&N.has anyone installed a K&N filter? I know that they allow more air, they also pass very fine dust particles (I've seen this in other engines I've used K&N on)
will it void the warranty?
GDE Tuning said, "We do not recommend K&N style filtration on a turbocharged engine.
The hi-flow filters do have less pressure drop, but they let larger particles through the media.
These particles can reduce turbo compressor life over time.
Naturally aspirated engines can eat the larger particles without major issues.
The stock airbox is more than adequate for the Ecodiesel."