kcheves

For 2009 sports cars, the interval for air filter replacement is 4 years or 40K miles, whichever comes first. This is per the Porsche Maintenance Checklist.

+1 for using the OEM filter.

Lvt19672

I've been using K&N air filters in all my vehicles for the past 25+ years without a problem FTW!!!

Rikky001

Disagree that a good filter is a clean filter. A good filter would be dirty then it has done its job, if it is clean than all particles went through it.
A good filter is a properly sized filter for the air flow needed with the smallest pressure loss possible.
I have some experience with BMC filters on power boats but for my Porsches I stick to OEM. MAF a myth I would not say so as there are so many documented MAF problems related to a sportsfilter application. The myth can be busted if the MAF is taken out regularly for inspection and cleaning. At the end of the day changing the OEM air filter to a sports air filter will not have a HP increase, it will only make a bit more intake noise.

997_Toronto

I think I can't but agree with most on here...was looking to replace the stock filter with K&N to gain a tig more power but after looking at power graphs & feedback from forum members decided to stay witn stock as the gains were minimal at best.

cutlass476

I have a Werks 1 carbon fiber airbox, which utilizes ITG reusable filters. They work very well and thankfully are cleanable since they cost $350 to replace. The airbox is an after market design based upon the X51 airbox. It is the only after market airbox/filter system that actually improves performance over stock. Everything else is s waste of your money.

DutchNy

I run a K&N on my C4s and CTT, and have on other cars for years, I stand by it, they make a difference on throttle response IMO

RJKflyer

Have tried K&N in the distant past on several engines up to 420bhp, measured 0-60 and 30-50-70 times and absolutely no difference.

Only use OEM on this car (997.2TT) as it's a massively expensive engine... I'll settle for a little less intake noise for a little less bore scoring.

ChicagoSpeed996

OEM filters. Once race crew that I spoke with uses OEM filters only.

Lvt19672

Porsche runs bmc's in the 918.

kellen

Paper filter for me. Used to use K&N, but it wasn't for the gain, it was so I could reuse it. I usually change the air filter every year or two depending on driving, so if I can pick up a K&N for 50 or so it makes sense if I am keeping the car.

Never had a problem with K&N, nor did I ever feel my car was quicker, got better MPG. Strictly a reusable issue to me.

Hatzenbach

Define "easy" for me. Changing spark plugs on a 997 is a major pain in the **** (at least for me)

82_930

Well, after all of everyone's input, I stayed with the OEM filter.

Also changed the cabin filter, engine oil and filter, power steering fluid, front diff, rear transaxle & transmission fluids, bled the brakes, flushed the coolant and changed the plugs. The car is 10 years old...and preventative maintenance after this about of time is a good idea.

I think that about covers everything, but now I am thinking, should I change the clutch fluid? Or was that already covered when I had my guy do the transmission fluid? Also, does the '06 C4 have a fuel filter?

I guess that I will have to give him a call.

SAN997

Not true. Air flow follows a principle analogous to electrical resistance. In this case, the air filter is in series with the rest of the intake system. So reducing air filter resistance will decrease total intake resistance. Not saying its a big effect, but the air filter is in series, not in parallel, so it does have an effect.

Rikky001

Think you have misunderstood previous reply. If the air pressure loss from the air filter is less than the restriction on the exhaust, the backpressure loss on the exhaust will have the biggest significance. In other words, an air filter pressure loss of 0 with no air filter installed will not give a better result

DC911S

Looks like we have a battle of fluid dynamics coming....