Magnaflow Muffler

[grizzly700fi]

Im looking for a muffler that is louder than stock but not going to have horrible drone. Gonna keep it all stock except muffler and 4" tip x5 and just clamp it over the tailpipe(are the magnaflow tips clamp on?). I love the sound of this truck

its a 5x8 oval 18". Is there much diference between the 4x9 and 5x8 or round with a 3" SI/SO? My biggest question is what fits the best centre/centre, centre/offset or same side offset? Im ordering from here so if you think there is an exhaust that i would like better plz tell me. I assume the muffler will be too short so where can i get extra piping?

First time changing muffler so want to do it right.

[MotoMedic]

Similar questions being asked in this forum further down the page. No real muffler experts have stepped up to answer those & your questions.....

 

http://www.gm-trucks.com/forums/index.php?showtopic=112540

 

 

I have the 3" in/out 5x11x22... good sound but only slightly louder than stock (and mine dumps just before rear axle)

[trucc_boi]

you want a center/center if you are just replacing the muffler and that muffler in the youtube clip is the exact muffler that I have.

 

i have a link to my youtube clip and exact page i ordered from on amazon in my signature. i would order from amazon and take it to an exhaust shop to get the muffler, the extra tubing, and the exhaust tip welded on. i think the clamp tips look cheap.. especially if your stock tip is inside it.

 

good luck.

[700 sportsman]

I too had a mangnaflow muffler welded in, mine is a 5"X8" oval and has an 18" long case, I think it has a much better sound than stock, but not the raspy straight pipe sound. I had to go with a 5x8 oval to get the configuration I needed, but generally the smaller the case the louder it will be. So if you want louder, I would with a shorter case or a round one. Also while I was deciding, I gave magnaflow a call and they were extremely helpful, so it may be worth while giving them a call. For the tips I was going to get a magnaflow, but I wasn't gunna spend $75+ on a tip, so I found that summit had weld on 304 stainless tips for about $30 shipped.

There's a link to a video in my sig. and if you want any pics. of the tip let me know

[trucc_boi]

magnaflow exhaust tip

 

here's the magnaflow exhaust tip i ordered and got welded on.

[700 sportsman]

Hmm, I can't believe I missed those when I was looking. O well I guess

[grizzly700fi]

iv decided to get the stainless steel oval 5x8 x18 3"in/out centre to centre hoping it will go in fine. If i have the exhasut exit same as stock what is the longest tip i can get? Would it be better to have it exit at the rear?

[700 sportsman]

For the length of the tip your just have to measure from the end of your tip now to where it starts to bend, and if you see your stock pipe under the tip, just cut it off way back in there. And about the exit, that is debatable, but to minimize drone and keep a fairly stock look, that would be your best bet.

Here's some pics of my exit location/tip:

 

[grizzly700fi]

So i plan on getting a stainless steel - magnaflow 4"x12" and exit same as stock. Would it be better to go with a 3 or 3.5? Only reason I want a 4 is for looks. Am i gonna lose any hp i know it wont be noticable just want to know. better to go with 3" tip to keep backpressure?

[700 sportsman]

I would stick with a 3 or 3.5" I personally think big tips are for diesels only, but that's just my opinion, as for the power/backpressure, I wouldn't really worry too much about it with just the tip, now the whole piping yes, but the tip will make minimal difference

[grizzly700fi]

Any noticable sound difference between the tips? how do i know which end is the inlet and which is the outlet on the muffler? the muffler needs to go a certain way right?

[MotoMedic]

So i plan on getting a stainless steel - magnaflow 4"x12" and exit same as stock. Would it be better to go with a 3 or 3.5? Only reason I want a 4 is for looks. Am i gonna lose any hp i know it wont be noticable just want to know. better to go with 3" tip to keep backpressure?

 

A little FYI about backpressure:

"

The myth and why it's wrong

One of the most misunderstood concepts in exhaust theory is backpressure. People love to talk about backpressure on message boards with no real understanding of what it is and what it's consequences are. I'm sure many of you have heard or read the phrase "Engines need backpressure" when discussing exhaust upgrades. That phrase is in fact completely inaccurate and a wholly misguided notion.

 

Some basic exhaust theory

Your exhaust system is designed to evacuate gases from the combustion chamber quickly and efficently. Exhaust gases are not produced in a smooth stream; exhaust gases originate in pulses. A 4 cylinder motor will have 4 distinct pulses per complete engine cycle, a 6 cylinder has 6 pules and so on. The more pulses that are produced, the more continuous the exhaust flow. Backpressure can be loosely defined as the resistance to positive flow - in this case, the resistance to positive flow of the exhaust stream.

 

Backpressure and velocity

Some people operate under the misguided notion that wider pipes are more effective at clearing the combustion chamber than narrower pipes. It's not hard to see how this misconception is appealing - wider pipes have the capability to flow more than narrower pipes. So if they have the ability to flow more, why isn't "wider is better" a good rule of thumb for exhaust upgrading? In a word - VELOCITY. I'm sure that all of you have at one time used a garden hose w/o a spray nozzle on it. If you let the water just run unrestricted out of the house it flows at a rather slow rate. However, if you take your finger and cover part of the opening, the water will flow out at a much much faster rate.

 

The astute exhaust designer knows that you must balance flow capacity with velocity. You want the exhaust gases to exit the chamber and speed along at the highest velocity possible - you want a FAST exhaust stream. If you have two exhaust pulses of equal volume, one in a 2" pipe and one in a 3" pipe, the pulse in the 2" pipe will be traveling considerably FASTER than the pulse in the 3" pipe. While it is true that the narrower the pipe, the higher the velocity of the exiting gases, you want make sure the pipe is wide enough so that there is as little backpressure as possible while maintaining suitable exhaust gas velocity. Backpressure in it's most extreme form can lead to reversion of the exhaust stream - that is to say the exhaust flows backwards, which is not good. The trick is to have a pipe that that is as narrow as possible while having as close to zero backpressure as possible at the RPM range you want your power band to be located at. Exhaust pipe diameters are best suited to a particular RPM range. A smaller pipe diameter will produce higher exhaust velocities at a lower RPM but create unacceptably high amounts of backpressure at high rpm. Thus if your powerband is located 2-3000 RPM you'd want a narrower pipe than if your powerband is located at 8-9000RPM.

 

Many engineers try to work around the RPM specific nature of pipe diameters by using setups that are capable of creating a similar effect as a change in pipe diameter on the fly. The most advanced is Ferrari's which consists of two exhaust paths after the header - at low RPM only one path is open to maintain exhaust velocity, but as RPM climbs and exhaust volume increases, the second path is opened to curb backpressure - since there is greater exhaust volume there is no loss in flow velocity. BMW and Nissan use a simpler and less effective method - there is a single exhaust path to the muffler; the muffler has two paths; one path is closed at low RPM but both are open at high RPM.

 

So how did this myth come to be?

I often wonder how the myth "Engines need backpressure" came to be. Mostly I believe it is a misunderstanding of what is going on with the exhaust stream as pipe diameters change. For instance, someone with a civic decides he's going to uprade his exhaust with a 3" diameter piping. Once it's installed the owner notices that he seems to have lost a good bit of power throughout the powerband. He makes the connections in the following manner: "My wider exhaust eliminated all backpressure but I lost power, therefore the motor must need some backpressure in order to make power." What he did not realize is that he killed off all his flow velocity by using such a ridiculously wide pipe. It would have been possible for him to achieve close to zero backpressure with a much narrower pipe - in that way he would not have lost all his flow velocity.

 

So why is exhaust velocity so important?

The faster an exhaust pulse moves, the better it can scavenge out all of the spent gasses during valve overlap. The guiding principles of exhaust pulse scavenging are a bit beyond the scope of this doc but the general idea is a fast moving pulse creates a low pressure area behind it. This low pressure area acts as a vacuum and draws along the air behind it. A similar example would be a vehicle traveling at a high rate of speed on a dusty road. There is a low pressure area immediately behind the moving vehicle - dust particles get sucked into this low pressure area causing it to collect on the back of the vehicle. This effect is most noticeable on vans and hatchbacks which tend to create large trailing low pressure areas - giving rise to the numerous "wash me please" messages written in the thickly collected dust on the rear door(s).

"

[700 sportsman]

Any noticable sound difference between the tips? how do i know which end is the inlet and which is the outlet on the muffler? the muffler needs to go a certain way right?

 

The larger tip will probably have a deeper rumble, but only really noticeable at idle, or at least that's what I've heard a few times. Also with magnaflow mufflers, it doesn't matter which way it goes, as it is a packed straight through muffler, not chanbered. as a matter of fact, mine is "technically" the wrong way, but that's the only option I had, but it doesn't matter what so ever