how often do we need to replace em?

 

Right, unless it gets really bad, just take it out, clean it, and put it back.

Maybe every 30,000 miles or so you might want to change it.

 

Just passed 20K miles... will have the guys at NTB in St. Charles take a look at it next week maybe and see how much its, ahem, filtered I guess.

 

the HKS i'm changing them every 5k miles. K&N is good for 20 25 K miles then clean them and put it back.

this is how i do it.

 

I thought the HKS filters were like he K&N filters, except that you don't have to oil them. At least that is what the tuner shop told me where I bought mine-and I would trust what they tell me since they know their stuff.