Flowmasters

[Zbec]

Flowmasters website says that their mufflers can increase gas milage my 1-2 mpg. Is it true??? Im lookin to put a true dual super 44 cat-back on my 99 1500 5.3 V8

[94_c/1500]

On my V6, I got 1 mpg better going with true duals and Flowmasters.

My dad had a '97 with a 350 and got 3 mpg better.

[KTMRACER]

IIRC most people claim better mileage with magnaflows moreso than flowmasters. I have heard from some people that flows decreased their mileage slightly on a single pipe system, magnaflow was the opposite.

[Zbec]

Ok, i just dont wanna have a huge decrease of like 2 mph or over that

[94_c/1500]

You should never loose mpgs by reducing backpressure.

[88Vic]

You won't lose any with a Flowmaster, you'll just gain more with a Magnaflow.

[94_c/1500]

Originally Posted by 88Vic

You won't lose any with a Flowmaster, you'll just gain more with a Magnaflow.

Dyno results?

[crossy's son]

no dyno results needed...

vs.

[88Vic]

Since when is fuel economy measured on a dyno?

Magnaflows put out better CFM numbers in flow tests, therefore flowing more and decreasing restrictions which in turn will increase exhaust velocity, increasing torque meaning less throttle needed to move the truck. Therefore, Magnaflow is better for economy.

[94_c/1500]

You are comparing an x muffler to a single in/out. The muffler you are showing is a glasspack.

[94_c/1500]

How much cfm does it take to change 1 hp? 1 ft-lbs, or 1 mpg?

[crossy's son]

Originally Posted by 94_c/1500

You are comparing an x muffler to a single in/out. The muffler you are showing is a glasspack.

thats the way all magnaflow mufflers are made..

if you think its a glasspack then type in "magnaflow cutaway" on google image search and you see what comes up...

[94_c/1500]

I didn't google it, but if it is not fiberglass then it is stainless. It still has the same design as a glasspack. Perforated tubing

[94_c/1500]

No X pipes in these mufflers. http://www.magnaflow.com/02product/u...asp?shape=oval

If you want the best MPGs for your 5.3 by changing your exhaust and use Flowmasters, use Super 44s. They are supposed to be better than 40s. Not sure, I haven't bought mine yet to see how they do. Also, thunderbolt cats work great. You might want to get an x-pipe or an h-pipe. The x-pipe is the better choice. If your plans for the truck are to keep it mostly stock, use 2 1/4 dual pipes.

[88Vic]

The difference being glasspacks generally use louvers, not perforated tubing. The packing in a Magnaflow will slightly distort within the first few hundred miles but after that it muffles the sound greatly and produces a very deep and toned rumble, much unlike the popping and snapping of standard glasspacks. Also perforated tubes flow better than louvers as they don't create as much turbulance.

And where on that page does it say the dual in dual out mufflers don't have x-pipes inside?

[crossy's son]

you seriously don't think thats a magnaflow

Its called...Dual in/dual out... its designed to do all the crossing inside so you don't have to run a Xpipe/Hpipe when running true duals. MAGNAFLOW takes care of that for you inside their mufflers !!!

[94_c/1500]

I am not saying it is not a Magnaflow. I am saying not all Magnaflows are made that way. Lets get back on topic.

[88Vic]

That's not an issue, any of the Performance model Magnaflows are straight through, and it;s a much better design than a louvered asspack.

[jbreshears]

how are flow masters on a 6.0?

[Zbec]

Alright soo does dual 44s with an x pipe sound good? Im not really lookin to increase even tho itd be nice mostly i just dont wanna decrease