I want to change the muffler on my '01 Screw, leaning towards Magnaflow right now. Not sure if I'll do a complete cat back or muffler change only. I put a 18" glasspak on my '99 F150 kept the stock tailpipe (son's truck), yep it was cheap and has good sound. A lot of people bash glasspaks and they have a bad reputation. But tell me something; doesn't straight through mean straight through. Outside of Magnaflow being constructed of better quality material and lasting longer with probably a little better sound due to better packing is there any REAL difference between the two. Isn't it the same concept. I tow a pretty heavy load with my Screw so Sound is important but Torque is #1. I lost torque on my '99 until I did the airbox mod and K&N.

The Magnaflow says it increases torque, is that because is a 22" long muffler body. Man, the stock muffler has a 32" body, this thing is like a garbage can.

 

surely someone has an opinion on this. aren't they all the same from a performance stand point? straight pipe, glasspak, magnaflow, dynomax ultraflow.....is the ONLY difference in sound quality. they are all straight through

 

Many of the performance mufflers now use specially designed baffles to arrest sound. These chambers can allow for almost strait thru performance with less sound or similar sound to the glass packs without using packing. The problem with glass packs is they burn out after a short period of time. Also, strait thru is not necessarily the best thing for our trucks.
I have a Flowmaster. I am not sure if I lost any bottom end because I did that and larger tires at the same time. It seems to me to be just fine. Some say Magnaflow is the best for torque but no one seems to have any real measured data.
My truck seems to run fine. I think it is because I kept the stock exhaust except for replacing the stock muffler with a Flowmaster 40 series. My truck has a real aggressive sound to it. Most people would not want to go any louder then the 50 series mufflers from Flowmaster. After towing a 5th wheel to Florida, given that I have 430 gears, I am now looking for something a little quieter. At highway speeds, under load, the Flowmaster 40 really got loud.
Another muffler I have recently seen that seems to have some following is the Spintech Muffler. It also uses chambers to cause the gases to spin within the muffler and thus arrest some of the exhaust noise. They still sound aggressive and if you go to their website they have sound bites of a 4.6 Mustang that should be similar to how our trucks will sound.
I don't know if I helped you or made you more confused but I would stay away from the glass packs.

 

thanks for the comment WLF. I am not putting a glass pak on my truck, gonna go with better quality. However, my real purpose of the post was to get some opinion on why is magnaflow better, and said to produce more torque when the design is virtually the same as a glasspak or other straight through design. I understand that baffeling of a straight through muffler affects sound but can't understand how or why one straight through design is superior than the other as far as increasing HP and TQ. Magnaflow, Ultraflwo, Borla, Glasspak, etc. how can one be better than the other from a performance standpoint when they are basically ALL the same. Some may say "the engineering is better in system A than system B", If all CatBacks us stock hangers then I suspect EVERY mandrel bent tailpipe is bent exactly the same as the stock pipe therefore the only potiential for gain is mandrel vs crimped bends. Doesn't that mean that the only difference is any CatBack vs any other is back to the muffler, once again what makes one muffler better than the other. Can the scavenaging of a straight through muffler be better than a chambered muffler, if so how? Maybe I'm looking for an engineering explanation and just haven't heard it. Everybody says their system is better but who can actually prove it.

 

Well said and asked many times, with no good answers. I see a lot of good exhausts that would work fine if I was running NASCAR or even had a Lightning with lots of x-tras.
This actually gets me to the question of the Y pipe. I looked at mine and the left enters the right at a 45 degree angle. It looks really good and what more does a stock (or close to stock) 4.6 need.
I really think the best thing to do is go to the various sites and listen to what they have to offer (sound bites). Then pick the one that sounds the best to you and gives you the best value and quality. If we stay with the 2.5 inch piping then there should not be too much of a problem as far as back pressure is concerned.
I hope!!!

 

i think that these new fords have to have a catback system to have a great sound. If i were you, i would buy the magnaflow catback. It may cost a little more but the look and overall sound will make you glad you did, trust me! The look of dual chrome tips and a roaring sound makes me glad i put a catback on.
As far as performance, a catback with muffler will keep torque with 2.5 inch pipe. No exhaust change in a stock ford pu will give you anything to crap your pants about. Go with the catback and wither glasspack or magnaflow youll be glad you did
Patrick

 

I just had a 22" Magnaflow put on my Expy 5.4 using 2.5" pipes. Good sound with acceleration, very quiet while cruising.

 

was the 22" Magnaflow a single in/out or single in dual out? was the muffler 3 " I/O with 2 1/2 pipes or 2 1/2 I/O. I am gonna run the stock tailpipe which i think is 2 1/2. Getting a lot of suggestions to go with a 3" I/O muffler. My thinking is that may slow velocity down inside the muffler. The muffler is going to flow so much better I think the 2 1/2 may be the way to go and not loose bottom end.

 

The muffler is a 3" single I/O. I had them fit the 2.5" pipes to it. They used the center/offset 5x7" oval muffler #12589.

The center/center version #12579 is the one listed for the Expy but the installer thought he could get a better fit with the center/offset.

There is not a 22" muffler with single 2.5" I/O in the 5x7" oval.

I had done the same thing with a 3" Gibson muffler but so far I am liking the Magnaflow better. (The Gibson recently broke at the neck).

Good luck.