Hamops wrote: It seems to me that putting on an after-market air filter on the intake of a diesel, makes no sense. The reason that I say that, is because the turbo compresses the air in the intake chamber so there is allows positive air pressure to feed to the engine. The turbo is quite capable of sucking all the air it needs to provide that pressurized air.
It is quite capable. The problem is, that for it to work harder to do this, and overcome unnecessary (oem) restriction, it must create power-damaging heat in the air charge. It does so with a higher shaft rpm also...decreased turbo longeveity.
But KN, as an example, cannot fix a problem unless it knows where the problem is. I can factually say, they are a clueless company, they trade your $300 for $ thousands in potential longevity issues. What a deal.
Diesel engines are real sensitve to dust particals, especially the new common rail diesels. Dust will destroy a diesel engine if it gets by the filter, be real careful what filter you use.