And is there any significant difference from the OEM paper filter?

I used to have a K&N drop-in filter for my 96 Civic. There was a noticeable difference in air flow and engine oil which became dark (dirty) rather quickly. I am kinda wary of the filter. Will it let a lot of dirt into the engine?

 

Supposedly you get a 4hp gain. No one has complained of extra dirty oil... but I don't think anyone has checked either.

 

I've had my filter for about 5 months, and the oil stays fairly clean. It doesn't come out looking like diesel oil from a truck, it has a slight brownish-red tint look, and it is translucent. Has anyone had a problem with residue buildup in the mass air sensor?