Dirty vs. Clean Air filter

[jesilvas]

So usually you hear "If you change your air filter you'll get better gas mileage." May be true. I've seen a magazine article (some diesel one) about how it didn't really affect mileage but response and power more than anything. Also it will affect your EGTs A WHOLE FREAKIN LOT
Maybe you guys know this but it just kinda donned on me. Just replaced my DIY filter and used a 4" exhaust piece instead of a 3.5" PVC coupling (almost the same size). Usually it would take forever, say 5+ mins to idle down to 300*. I can get there in about 1. Just thought I'd share and enlighten someone else who never really thought of it like I didn't before

[Cutty72]

Yeah, when I bought my pickup, the air filter was packed full of mud and dirt, can't believe it even ran. Bought a new one right away, didn't help mileage any, but sure helped the get up and go.