I have an '05 4.7 auto. +1 to tdmopar, got to get it breathing better. I had the stock muffler replaced with a magnaflow and I noticed about a 1 mpg increase in fuel mileage. I have amsoil on order, or should I say back order because thats what my ticket says. Switching to synthetic oil can increase mpg too from what I have seen. Yet to test it though. Next on my list is a CAI when I save up the money. After that it has to be the SCT Tuner. I'd like the tuner now but the money for it isnt available yet. All the modifications I would like to make should help with mpg and even increaseHP. Get the best of both worlds :-)

I forgot to note that I get around 16 mpg in town and upwards of 18.3 on the highway.

 

Just got rid of my 02 QC 4.7 for a 07 QC 4.7 ( life-time powertrainwaranty) and with the 02 and K&N, lid only I would get 21 - 22 on the Highway under 70 MPH. Hope the new one get the same.

 

I dropped in a K&N filter in thestock air box on my 06 Hemi, the exhaust was hacked up by the previous owner, he moved the resonator, muffler and tailpipe and installed a Flowmaster with no tailpipe. The exhaust just dumps under the truck, but I have a Borla cat back system on it's way.

I am currently getting between 18-20MPG with most of my daily commute on the interstate.

I can't see how installing a CAI could increase my mileage in a cost effective way, as the stock system seems to flow well with the K&N. With the CAI systems going for around $300.00, I can't see how this is a cost effective way to get better mileage, or performance IMHO.