Flowmaster vs Magnaflow vs Other

[Skillet]

Personally I think it's tough to make a v6 anything sound good. Most all of the responses you're getting here are based off of a v8 engine that sounds totally different than a v6. I don't know what to tell you knowing it's a v6.
 

Oh.  Never mind on the two chamber flowmasters with the 4.3 - it will just make it sound bad louder.  Its a good motor for sure, but doesn't work well with a megaphone like the FM.  Go with a good engineered borla (or other) specifically for your application.  Sound aint worth giving up torque with your rig, IMHO.

[270Shooter]

I have an original 40 flowmaster on my 5.4. ford. Its not that loud, but it still has stock pipes too. I like it because it is louder than stock and has a good tone. I think magnaflow sounds better as your rpms rise though. Magnaflow seem to be quiet at idle compared to the flowmaster though.

[jackelope]

My buddy's got a Magnaflow setup on his v6 Jeep that sounds good. Not loud, just a little throaty. Lots of info and videos on YouTube. 

[dscubame]

Flowmaster vote here without the smallest doubt.

[DoubleJ]

Personally I think it's tough to make a v6 anything sound good. Most all of the responses you're getting here are based off of a v8 engine that sounds totally different than a v6. I don't know what to tell you knowing it's a v6.
 

Try it straight piped.  I tried about 4 different mufflers on my 300 i6 on my 1992 f-150 and now have it straight piped.  Sounds really good for what it is.  Raydog, if you make it to the fishtiq bbq later thing month, you can hear it

[paulf919]

Take a peek on YouTube for some exhaust clips.  I'm sure there are some good vids on there.

[raydog]

Personally I think it's tough to make a v6 anything sound good. Most all of the responses you're getting here are based off of a v8 engine that sounds totally different than a v6. I don't know what to tell you knowing it's a v6.
 

Try it straight piped.  I tried about 4 different mufflers on my 300 i6 on my 1992 f-150 and now have it straight piped.  Sounds really good for what it is.  Raydog, if you make it to the fishtiq bbq later thing month, you can hear it

Can I straight pipe my exhaust will all of the o2 censors? What is the fishtiq bbq?

[Thefisherman83]

If you went straight through from the heads it would be stupid loud and you would lose power.  You need some back pressure for your low end.  Keep your cats and chop your muffler, see how it sounds.  If you like it weld on a straight pipe, if not pick a good muffler.

[TheKid#10]

Magnaflow.

[JackOfAllTrades]

If I was to spend money for exhaust on a 4.3v6, (which I probably wouldn't), I'd dual exhaust it, keep the pipes small for some back pressure, install a cross-over tube as far up stream as practical, install dual cheap Thrush/Summit turbo mufflers with pipes extending/exiting behind the rear wheels.
 
Why? Because the price of the Flomasters/Borla/Magna will never make that V6 sound like a V8. None of them will give a good return on money spent to improve power. But, if you want it not to sound stock, A cheap dual set up like this sounds 'pretty' good and will give you just a little more power.
 
-Steve

[raydog]

If you went straight through from the heads it would be stupid loud and you would lose power.  You need some back pressure for your low end.  Keep your cats and chop your muffler, see how it sounds.  If you like it weld on a straight pipe, if not pick a good muffler.

I ran it when i cut the exhaust off just after the cat. It sounded like a tractor and was terribly loud.

[DoubleJ]

raydog, I sent you a PM

[Thefisherman83]

If you went straight through from the heads it would be stupid loud and you would lose power.  You need some back pressure for your low end.  Keep your cats and chop your muffler, see how it sounds.  If you like it weld on a straight pipe, if not pick a good muffler.

I ran it when i cut the exhaust off just after the cat. It sounded like a tractor and was terribly loud.

I meant just cut out the can, leave the rest of the pipe there.  Or you could go with a set of "off road" headers and a good muffler, that would add power and sound. 

[DoubleJ]

If you went straight through from the heads it would be stupid loud and you would lose power.  You need some back pressure for your low end.  Keep your cats and chop your muffler, see how it sounds.  If you like it weld on a straight pipe, if not pick a good muffler.

*Best caveman voice*

NO.  BACK PRESSURE BAD!!!

Read:

There is a common misconception that engines need backpressure in order to run properly, generate low end torque, etc. That is simply untrue. Backpressure is a bad thing. Always. Take a look at a top fuel dragster...how much backpressure do you think those zoomie headers make? Very little, and those engines produce 6500 hp.

So, what is backpressure? Any fluid flowing through a pipe experiences drag on the walls of the pipe. This depends on a number of factors, including the diameter of the pipe, the smoothness of the inside of the pipe, the viscosity of the fluid, and the velocity of the fluid. This drag results in a pressure drop through the pipe. In order for the fluid to flow at all, the pressure on one end of the pipe must be higher than at the other. In an exhaust system, that pressure drop is what we refer to as backpressure. It's pretty obvious that the engine has to produce this pressure differential, so the less power it has to spend making pressure to push the exhaust out, the more power it can send to the wheels.

Given that exhaust pipes are pretty smooth, and that we can't change the viscosity (thickness) of the waste gas being forced through the pipes, we are left with basically 2 parameters we can have any control over: The pipe diameter and the gas velocity.

Unfortunately, the pipe diameter controls the gas velocity since the volume of gas is prescribed by the engine. So, we really only have one thing we can change. So, bigger pipes allow less pressure drop for a given volume of gas because the velocity is lower. The pressure drop (backpressure increase) is proportional the gas velocity squared, so if I double the gas velocity (by reducing the cross sectional area of the exhaust pipe by half) then I quadruple the pressure drop.

Well, there's an easy solution for that: Just make the exhaust pipe bigger. Bigger pipe, lower gas velocity, less pressure drop, so less backpressure. Wow, that was easy. After all, this is the way it's done for basically any type of commercial plumbing system. Need less pressure drop on a chilled water pipe or a natural gas line? Just make the pipe bigger.

But wait, there's a problem....Having a huge exhaust pipe has killed my low end torque!!! What's different? Oh, there's no backpressure!! Therefore backpressure makes torque!

Wrong.

An exhaust system is different than just about any other plumbing situation. How? Because the flow is pulsed, and this turns out to be a big deal. Every time a pulse of exhaust gas runs through the pipe, a strange thing happens: it as it passes, it has a little area of vacuum behind it. Just like a NASCAR stocker running around the track, the pulse generates a little bit of a vacuum behind it. In NASCAR, a driver can take advantage of another driver's vacuum by getting right behind him and driving in it. The wind resistance is drastically reduced. This is called drafting.

Well, how big the vacuum behind each pules is depends on the gas velocity. The higher the velocity, the bigger the vacuum the pulse has behind it.

Now, this means that I can "draft" the next pulse, just like in NASCAR. In NASCAR, it's called drafting, in an exhaust system, it's called scavenging. You've probably seen this term used when talking about headers, but the same concept applies in the pipe.

I get the maximum scavenging effect if the gas velocity is high, so the pipe needs to be small. By maximizing the scavenging effect, I help to pull pulses out of the combustion chamber, which means the engine doesn't have to work as hard to do that.

This has the most effect when there's a bunch of time between pulses...in other words, at low rpm. As the revs rise, the pulsed flow becomes more and more like constant flow, and the scavenging effect is diminished.

So, at low rpm I need a small pipe to maximize scavenging, and at high rpm I need a big pipe to minimize pressure drop. My exhaust pipe can only be one size, so it's a compromise. For a given engine, one pipe diameter will make the most overall power (i.e., have the largest area under the curve on a dyno chart).

So, the loss of torque has nothing to do with backpressure, and everything to do with gas velocity. So you need exhaust components that are not restricive (manifolds/headers, mufflers) and that are sized correctly for your application.

To further dispel the "backpressure is necessary" theory, try this if you want. If you have access to a vehicle with open headers, make a block off plate that will bolt to the collector. This plate should have only a 1" hole in it for the exhaust to flow through. That will give you PLENTY of backpressure, and zero scavenging. Then you can report back on how much low end power it has.

The one exception to sizing an exhaust is for turbo cars. Since the turbo is in the exaust stream, the gas flow spinning the impeller tends to come out of the turbo with the pulses greatly diminished. In this case, you can get away with running a larger pipe than on an equivalent HP N/A engine because you can't take as much advantage of the scavenging effect.

[JackOfAllTrades]

So, at low rpm I need a small pipe to maximize scavenging, and at high rpm I need a big pipe to minimize pressure drop. My exhaust pipe can only be one size, so it's a compromise. For a given engine, one pipe diameter will make the most overall power (i.e., have the largest area under the curve on a dyno chart).

So, the loss of torque has nothing to do with backpressure, and everything to do with gas velocity. So you need exhaust components that are not restricive (manifolds/headers, mufflers) and that are sized correctly for your application.

You only needed to write that above... Since the OP is about what muffler to install,   I avoided such, by allowing that most people don't need to know the complete explanation of scavenging. Which is tunable with header tube length and diameter changes.  A little back pressure in the form of restriction which increases velocity as those gasses get more dense by heat, as they exit the restriction, for a 160hp street engine allows the exiting gas pulse to pull on the next one as the exhaust valve is opened but is probably not even messurable in terms of power gain with stock manifolds and catalytic converters in line. A little back pressure actually dispells the exhaust pop out the tail pipe.
 
He's not working on a race car!
 
In REALITY,  my son gutted the cat on his truck. Installed a Super44 FM, 3" in, dual 2 1/4" out to tail pipes and lost seat of the pants low end torque. That's a pretty free flowing exhaust system with factory exhaust manifolds on a ~stock 360mopar. Very little back pressure, (a crappy term that should just be refered to as restriction). It felt stronger off the line with the stock muffler in line.  But, as the exhaust charicteristics did change the low end performance, the mid-upper range of performance seemed to improve.
 
 
-Steve