Which Air Filter?


My air filters turned a nasty colour with all the dirt trapped inside it so am going to change it instead of messing around cleaning it. What would you's say was the best one to go for? i know alot of you's are running hks/blitz etc but is there one that has the advantages over the other or are they all the same? Need something that will cope with big power....


Staff member
I use an M's K&N, use the cleaning kit now and again at its been spot on.
Me too... although I think mine might actually be a bit small.

It all depends what you want from your filter and where you'll be driving.
For road use you can get away with a higher-flowing cotton filter, but for dirt and dust you can't beat foam... or a foam sock over your cotton filter.

There is a difference between them all, whether you'll ever notice it over the difference from stock is questionable.


Staff member
Yeah, I'm not convinced by that article; it says they've tested the power gains, and there's results for it... but no more details (like how many runs they did).
I appreciate that it's definitely the best filtering, and if there is no vacuum drop across it that has to be the best filter.

I'm disputing the science of what they've done rather than your decision!
I guess what I'm saying is that I don't believe there's much difference between any of them; they all stopped using really sticky oils when they realised it upset the AFM. An improvement of 1bhp over the other filters is not statistically valid (nor has it been shown to be significant) because you can get more than that between runs on the rolling road. - There is no evidence of experimental design, and it's the kind of pseudo-science that Myth Busters would do (and as an analytical chemist I can't let go of this kind of thing - you should hear me lay into CSI).

I guess if they are all the same price (as the article suggests), go with the A'Pexi... if they're not pick what you like because it doesn't really make that much difference. (It is hard to dispute that filtration test though.)
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New Member
i use a k&n also i managed to get one the same size as the m's one as my m's had lots of tiny holes in it and it chipped my turbo wheel

geoff pine

Well-Known Member
Blitz the 1 with mesh filter bought on ebay for £35 with a maf .I had a HKS mushroom filter but it would of cost £20 for a new filter .

fubar andy

Moderator & N/W Rep
Staff member
The other thing about HKS filters is they seem to have a tendency to degrade if not replaced and you could end-up sucking in bits of foam into the engine…


A'PEXi here too. Had an M's K&N before that. Only reason for change was that someone nicked the K&N when the car was stored away a couple of years ago. :x

Fast Guy

Staff member
Buy the green foam HKS one and find out.;-)

They can fall to bits (see above), be too restictive, not filter well enough, be too small for the job or block up too easily to name a few problems.