ORIGINAL: HankL

Spend a little time at the Flowmaster website.

Notice that everything is written about 'sound'
and very little flow measurements or dyno charts?

Flowmaster has spent millions of $ doing research to give a particular sound to the exhaust.
If you like that sound on a v8...buy the Flowmaster.

Reducing the backpressure in the exhaust can slightly improve MPG
but the effect is greatest at full throttle and goes down rapidly if you are driving at 'part throttle'.

Most driving is done at part throttle, especially on a Ram with a large V8.
Most of the time the exhaust backpressure is already only 1 psi or so at part throttle.

Lowering this backpressure by a tiny 0.2 psi won't improve MPG much in unloaded driving
but will if you tow a heavy trailer or cruise long distances at 90+ mph.

In 2002 Dodge put a new design exhaust system on the Rams that had significantly less backpressure than the 1994-2001 design. Notice in their advertisements that Dodge didn't brag about this new exhaust improving MPG in daily driving? That's because it didn't in part throttle driving like the city/highway EPA tests.

How much did the 2002 exhaust redesign help the full throttle horsepower at different rpms?
About 13 ft-lbs (293 versus 280)

Go to hypertech's website and compare their "stock' dyno graphs on
2001 Magnum 5.9V8s

http://www.hypertech-inc.com/images/...dodge015.9.jpg
against

2002 Magnum 5.9V8s

http://www.hypertech-inc.com/images/...dge02035.9.jpg

What muffler design has the lowest exhaust backpressure?

My opinion is that a 'straight thru' design
like the DynoMax UltraFlo
has no more backpressure than the same length of exhaust pipe,
and the slightly more expensive stainless steel construction will last longer.

This type of design is similar to the resonator that Dodge added to the stock system.