Has anyone replaced their factory airfilters with the K&N airfilters? I was just curious to know if anyone noticed any benefical results?? I was thinking about buying one and just wanted to know if it was worth it.

I have one and I didn't notice any difference from it. Of course that does not mean there weren't any gains but you just can't feel an extra 5 hp, no matter what anyone says.

I had a K&N filter in a Honda Civic I bought before this Grand PRix. I couldn't really tell the difference in it but i thought maybe it would be differnet with a larger engine. Thanks for the reply Jeff3800

I just replaced mine with a K&N. I did notice a slight difference, but I do agree with Jeff. It's real hard to notice a 5hp increase.

After having the K&N filter in for a couple of days, I can truly tell a difference in gas mileage. My mileage has increased 5 mile per gallon. I was getting the documented 18/28, now I'm getting 23/33. Well worth the $50 I spent on it.

Interesting...
How many tanks of fuel did you go through to see the 5 MPG increase (in a couple of days)? Did you just drive it lighter and look at the MPG display on the Driver information center? You may want to actually drive over a few of tankfulls to start to see an increase. I am curious if you ran the FTP 25 and HWFE chassis dyno tests that the manufacturers have to use to publish the emission and fuel economy numbers. The 5 HP is tough to see even on an engine dyno (run to run variability will be close to +- a couple of ponies in a environmentally controlled dyno cell). If you do see these increases, I would suggest you start working for the sales department at K&N :rolleyes:

Brad,
I did not buy my GTP to watch it sit in the garage and go out and wipe the dust off every 2 hours. I buy a car to drive. I have put almost 8K miles on my GTP since I bought it 2 months ago. In those couple of days, it was actually three days, I drove alot around town which I did use a full take of gas. I also went out of town, which again, I used a full take for the 'round trip. I am simply sharing the information that I have noticed since replacing my stock paper filter with a K&N. If you're not happy with my personal findings, nobody is making you read my postings.
Bobby "AustinGTP"

What is the average mileage that you should replace the air filter? I bought my GP at 47k and there is now 71k. Knowing the previous owner, I'm pretty sure it has never been done and I'm starting to see a substantial decrease in my mileage.

Thanks Everyone!

err...you put on 24k since you had the car...it's over due now...try to stick at the 10k mark to replace it...I check mine often and when it get's dirty I change it. I got my car in Feb. and put on 8k since then and had to replace the filter...that superchager suck's that air in...lol