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-   -   Drop-in air filter (

tonyturbo13 01-17-2010 09:23 PM

Drop-in air filter
Hey guys, I'm thinking of replacing the OEM air filter with an aftermarket one for better flow in my 09 WRX. I've seen a few different ones, K&N, Perrin, etc. I noticed that they range in price and I'm assuming they'll provide similar performance gains. Any recommendations based on personal experience? Thanks in advance for the feedback.

operadude 01-18-2010 10:31 AM

I have the K&N drop in filter in my 2008 wrx. When I went stage 1 with an XPT open source tune and the K&N drop in filter, the car went from running 14.4 stock, to 13.9 @ 95mph through the quarter mile. Thats half a second improvement! Your car should be quicker than that right out of the box but I'm sure you would see some improvement if you add the drop in filter + tune as well. Without a tune you will not notice much of a gain but the car will run perfectly fine.
If you wanted to get the stage 1 open source tune you would need to buy or borrow a Tactrix cable, download ECU Flash and Romraider (free) to your laptop, and buy a map online from tuners like XPT that have already designed a generic map for use specifically for the drop in filter, or contact your local tuner. The 2009 + stage 1 maps also require a bigger fuel pump.
[url=]XPT Stage 1 - 2009 WRX MT [XPT1401V] - $77.00 : XPT Tuning, The XPT Tuning Online Store[/url]

PdxRex 01-18-2010 12:46 PM

I have the K&N drop in, [I] found better air flowe and a little better response also I can hear my turbo spoll more !Thumbs Up on my 09 Wrx sedan

Smokin'Joe 01-19-2010 02:41 AM

I have the Perrin drop-in, but I looked at the K&N one as well. They're very similar and I went with Perrin to group with another purchase so it was all in one box. Vastly superior to the stock paper ones regardless of what you get, and in my view they pay for themselves if you get the cleaning kit and clean it twice (rather than having gone through 3 paper replacements). You'll never see it anyways so looks don't matter, lol. As mentioned, you might hear a little more of the turbo spool, but it's minimal. Still a much better flowing intake on the stock box and is said to yield around 5hp...

airplnmdls 01-19-2010 08:13 AM

I also have the K&N and at the same time did the snorkus delete, so I heard the turbo spool more, which I like. As for power I didn't "feel" a difference, but I believe their claims to be true...

tonyturbo13 01-19-2010 04:50 PM

Thanks for the input guys...looks like it's time to shop around for the best price, thanks again!

Wutangjn12 01-26-2010 07:00 AM

i will sell you mine for 25 dollars + shipping. i used it for 4-5k miles. works great with a stage 1/2 setup. but i have brought a AEM CAI.

tonyturbo13 01-26-2010 08:35 PM

Wutangjn12, I've PM'd you...

FACTION95 01-27-2010 05:23 PM

Can you run a drop-in panel filter without any type of fuel management ie, Access Port or tuning?

booosted09 01-27-2010 05:44 PM

yes sir.

chris02 02-02-2010 10:52 PM

i would suggest a cai instead i bought both and i never even put the drop in filter in i just used the cai... i got the k&n i will sell it to you for like 25 or 30+ shipping i never used mine just so you know. I highly recommend the cai my tuner did to me and i was very happy w/ the power it gives you i got an aem and you really feel the difference in pull at least i did but i did have other mods which could have helped.

synolimit 02-02-2010 11:04 PM

i wish i still had my K&N drop in, bought it and never used it. im going for a tune next saturday and if we have time i want to tune with my Turboxs CAI and then throw the stock unit back on to see the difference. wish i could then do a drop in but o well, we'll see what we see with the CAI vs stock back to back at least.

tam85 04-09-2010 03:59 AM

i also have the k&n "drop-in" [URL=""]air filter[/URL] for my wrx and i really like it! if you are on the market , i do recommend k&n drop-in filter. the cleaning is very easy although it is time consuming and can take up to 2 days for the k&n filter to completely dry.

10046252 04-13-2010 01:43 PM

I just put the Perrin drop in filter in my 10' WRX. Can't say that I "feel" any extra power. It definitely sounds mean and you can hear the turbo spool up...I can also hear the stock BOV. For 44 bucks you really can't wrong with this upgrade.

85z28 04-03-2012 06:37 PM

I added a K&N drop in filter and reset my ECU. I noticed a decent increase in acceleration. Of course the previous owner might have run less than 93 octane and resetting it helped. Definitely a good buy for 50 bucks.

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