Yes Marty you are very right, Your question was about the Muffler and you stated some facts along with it about your MPG experince. It seems by the 5th or 6th post you were getting the its a truck you going to have bad MPG.

 

Yeah, people get a little overzealous sometimes... oh well, no harm no foul.

 

Right, simple mix up.

 

True. I worked at Auto Zone some time ago, and the managers selling point for the Bosh+4 spark, he would say to the coustmer that it would give you a extra 20% on MPG. and of corse the dummies would believe him. My reaction to him was the same as yours. If thoes plugs are so good as you say thay are. The EPA would make all auto makers use them. Look people. If you worried about gas then doint drive a truck of any kind. Just keep the toes off the peadl and you'll wont push down as far

 

I can honestly say from 3 years experience that a better flowing exhaust will not improve mpg. I drove 80 miles a day for 5 years. I have a Magnaflow cat-back that does flow much better than stock. I gained about 12hp but is is all in the upper rpm range. I lost lowend torque whick is what you need in a heavy truck. I have a Airaid MIT pipe with a K&N drop-in filter and a Diablosport Predator. I run the 93 octane tune which returns the best mpg.
The stock exhaust nets better mpg in any configuration. usually about 1 to 1.5mpg better. Hemi's like backpressure. Even the Challenger guys complain about lost power after removing the cats and reducing the backpressure.
I currently run my Cat-back again because now I live less than 4 miles from work and am not spending $400 a month on fuel.

 

As soon as i put my first exhaust on i thought i had lost power... until the Upper RPMs. I kept my stock exhaust for this reason!

 

sometimes i wish i had my stock one, but it was about 1 month away from being rusted out and in need of replacement anyways. best way for good mpgs, 55 mph unless on a highway and coast down hills haha. thats what i do, got 16.13 last tank thats with some city driving in there as well.

 

I take every road i can find with 60 and under lol!

 

There absolutely is a mod that will increase mileage..

Install a vacuum gauge.. use it as you should..

Short version: keep as much vacuum as possible. It differs with varying mods, engines, intakes, environments, ect.. but let's say you idle at -15 inches..

Let go the brake, hit the skinny.. don't throttle any more than -5 inches.. wait for the shift.. let up on throttle a touch, keeping -5 inches.. wait for the shift.. keep same process until reaching o/d, where there will be a ton of load dropped on engine on that shift.. throttle back to cruising vacuum of no less than -12 inches...

In my truck, with my weight and overall ratio, I'm pulling 14~15mpg at -15 inches of vacuum.. the problem is holding it there... My truck averages about 14mpgs overall, and would do better if I could tolerate putting around all the time.. if you learn to drive based on engine load as represented by vacuum signal, and not traffic/speed limits, you'll be damn surprised what you can get out of these things... A $25 vacuum gauge mod is a helluva mod for saving gas..