Purpose of filter?

[N55_BBM]

Was wondering why people but those cone filters or even the new K&N filter that come out... does it change the noise the engine makes or is it for increased hp? I wouldn't imagine it would make such a difference over the stock filter, would it?

also, does it void warranty in any way? how easy is it to put the original filter back in?

[ScarecrowBoat]

I hope you are joking...

[N55_BBM]

I mean the purpose of switching the stock filter for another one in a stock car, should've made that more clear. I know what the filter is for, just don't understand why change it. I personally don't think it helps gain perceptible power especially because unless you have a good CAI it's going to suck more air in but it'll be warm air. And I really don't see a CAI in many of the 1ers out there...

[N55_BBM]

nvm, just saw the K&N filter drops into the factory box.

does it really help with the hp is what i meant to ask, is it noticeable? and since it's in a box i guess it doesn't change the sound of the engine...

those conic ones do tho right?

[mlifxs]

Originally Posted by N55_BBM

nvm, just saw the K&N filter drops into the factory box.

does it really help with the hp is what i meant to ask, is it noticeable? and since it's in a box i guess it doesn't change the sound of the engine...

those conic ones do tho right?

on my car, (328i) I did a K&N drop-in filter. I could tell a difference though it wasn't dramatic and no idea if it actually added horsepower. No difference in sound.

it DID improve highway fuel economy for me, by 1 to 1.5 miles per gallon, and I do plenty of highway miles on my commute. I figure it will pay for itself in a year.

[ScarecrowBoat]

Originally Posted by N55_BBM

I mean the purpose of switching the stock filter for another one in a stock car, should've made that more clear. I know what the filter is for, just don't understand why change it. I personally don't think it helps gain perceptible power especially because unless you have a good CAI it's going to suck more air in but it'll be warm air. And I really don't see a CAI in many of the 1ers out there...

It will make it louder, possibly more ability of air volume that it can intake, but it will be hotter. It also amplifies the "whooshing" sounds of the DV's and turbo. That's what I like about it, not the moderate power +/- (there are dynos that go both ways)

Originally Posted by N55_BBM

nvm, just saw the K&N filter drops into the factory box.

does it really help with the hp is what i meant to ask, is it noticeable? and since it's in a box i guess it doesn't change the sound of the engine...

those conic ones do tho right?

A K&N will provide a very mild HP/sound increase.