I am at almost 28K mi and had never replaced an air filter. It is due for replacement at 30K mi, but I am debating if I should replace it at all, or get something else instead of it.

Lately, my gas mileage had went down, in part to switch to heavier wheels. IGOR911 had replaced his stock air filter with brand new OEM and his gas mileage had worsened, and I dont want the same problem. Anything that will void warranty will not do. Any comments please.

 

If your air filter is dirty, you should clean it or replace it.. As for replacing the intake with aftermarket, you wont notice that big of a difference unless combined with other mods..
And I wouldn't worry about warranty.. You can always replace the stock intake b4 you visit the dealer..