K&N's don't filter well enough for a turbo engine. I had one, and I always had a little bit of grit inside my intake tube that had gotten through my K&N. AFE makes a good air filter that filters better and still flows as good, or you can use a BHAF like a lot of people do. The AFE's are reusable, and the BHAF are throw a way's.
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04.0 HO QC 4x4 LB auto transgo VB, stock, for now
Sold 91 now intercooled W250, 388HP 923TQ on #2 only 436HP 968TQ on meth
Work Truck, 93 W350 LE Dually 5Spd almost stock