I am thinking of installing a magnaflow muffler in place of the stock muffler on my 01' Screw. Has anyone done this? If so, how much louder than stock was it and did you see any performance or mileage changes. I want to improve low end torque and my thinking is that if I keep the stock pipes, I will keep enough backpressure in the system to do this. I have done the single 3" on other vehicles in the past with little effect. Actually, 95 Dodge 5.2l and 96 Chevy 5.7l both got worse in power and mileage. I also want something that is pretty quiet, not much loder than stock. Also, don't want to spend the $300+ for the Gibson or any other true Cat-Bac. Any info would be appreciated.

 

01lightning just had a Magnaflow 14468(D/I--D/O) installed today. It wasn't any louder than the stock L muffler at idle and up to 1500 rpms(no load). I left before he did and didn't get to hear it under load or at WOT--but it surprised me at how quiet it was. His L is stock with only 500 miles on it.

Dan

 

SCOTTS-CREW,
Hey did you put the magnaflow on yet.
What do you think of it if so ? I think going with the stock pipe will be the way I go in the future. Just swap out the muffler.
Put A nice big *** tip on too. 3.5-4" would be nice.

 

fallscrew,
I see you chose the gibson swepside. I'm thinking of doing the same. But, I keep asking myself about just swapping the muffler only. From your comments, would you have rather just replaced the muffler instead of doing the cat back? I want a little rumble, not alot of noise......and not spend as much $$...

 

Well I went and had an "Iron Case" muffler installed on stock pipes yesterday. The guy at the muffler shop said it was quieter than a Magna or Dynomax and is of better quality, also less money. All I can say is it is worth every penny. Just a little "bup bup bup" at idle and very quiet at highway speeds. The best part is the engine revs so much easier now. I can really feel the difference. It is not earth shattering, but it helped for sure. A noticable gain in the low end and mid rpms. Paid $101 out the door and it was done while I went to eat lunch.

 

Strongwind,
If I had to do it all over again I would just replace the muffler and find a nice 3 1/2"- 4" tip to put on . I think the Gibson sweptside is nice. I wanted better flow & more low end so that's why I chose the Gibson. It did make a difference but I think that I could obtain that with just a muffler .
The Gibson helped but not a great deal. I also think by keeping the stock size pipe & going with a free flow muffler would work better and get a better sound. I also tried a flowmaster si/do delta flow 50 series with 2.5" out the back & did not like it at all.
I lost ton's of power & had a lot of drone in the cab. I saved my stock system so when this one take's a crap I'll put the stocker back on with a free flow muffler. The Gibson 3.5" stainless tip is the best part of my exhaust.( Look's real nice) . If you think about it the only difference in the 2 would be the difference in the pipe dia. 2.5" vs 3.0" and that will not make any difference because the biggest restriction in the exhaust is the factory muffler not the pipe. Yes a 3" will flow better than than 2.5" but I think keeping the 2.5" would give better back pressure & low end torque then you can pick the sound with the muffler you want.
Sorry about the long winded post....Hope it helped ya!
later...Mike

 

Fallscrew/Scotts-crew,
Thanks for the info. Y'all have confirmed my thoughts.

I'm sure the Gibson cat back is a good deal and will help, I'm just not convinced for the additional $200+ I would see that much incremental benefit over the higher flow muffler. I'm looking for a little more low end and to make the truck "rumble" a little during acceleration - and not drone on the highway. Not like the glaspacks I had 20 years ago (now I'm sounding old....)

Scotts-crew - any other info on the "iron case" muffler? What shop did you have the work done? Any other manufacture info? It sounds like what I'm trying to do with my truck.

Thx again.

 

I should have called it Iron Case, not Iron Tuff.
Well, what I can tell you is this. I called every muffler shop in Colorado Springs and even one in Denver. Half of them didn't even want to talk about a muffler only, just a single 3" catback when I said I wanted torque. After a lot of research on this board I was ready to go with the Dynomax Turbo. The shop that did mine was a mom & pop shop called Discount Exhaust Works. I had called them earlier and they said the would install a "Turbo", so when I called back I asked if the "turbo" they had was a Dynomax, and it was, but the guy told me that he had a muffler of the identical design, quieter, and better flow for the same money. All I can tell you is he called it "Iron Case", sorry I called it Tuff earlier. Now, I did talk to another shop that installs the Iron Tuff and 3 other shops said it was junk, will start popping, backfires real soon.
The muffler looks good, about 7-8" dia, 18-24" long, alumanized.
The increase in torque is great and the engine just seems to be running easier, gets rpm's a little quicker and smoother. Even feels like it shifts a little differntly. IMHO, I would do this every time for 1/3 the price of a Gibson or others. The other thing is if I have a problem, I go to the shop here and it's taken care of.

 

I think changing the muffler is the way to go. I went with a single glasspak and kept the stock piping. I do not have any popping in my exhaust but do have a great rumble. Sounds great at idle and if you want more sound just push it a little harder. I have "0" drone in the cab at highway speeds. From what I have observed, glasspaks are prone to popping when you have duels. The single glasspak sounds great. There is differences of quality even in a glasspak. Mine is aluminized and is about 20" long.

When you look at a Magnaflow, DynoMax Ultraflow or a glasspak they are all very similiar. All are straight through design and should provide the same results. The Magnaflow will probably be quieter because the muffler body is bigger and can absorb more sound and I hear the Ultraflow is really loud. Now my Expy, will probably get a Magnaflow but I'm keeping my stock tailpipe. I use it to tow and gotta keep the torque up.

 

I swaped out the stock "gun safe" Ford muffler on my '01Screw
for a Magnaflow.
No changes in the stock pipes other than cutting and
reforming to a side exit in front on the rear wheel.
Sounds good, not to loud. Sorry, no info on mileage but the throttle
response with the KN air filter is better than stock.
Total cost installed, $ 130.00

NordicBastard

 

Scotts-crew,
Thx again. I'm looking around Houston.
A few of the places I've called are pushing the Dynomax, another the Flowmaster. All around $90 to $150 installed, depending on exactly what I get, tip, etc...
Just trying to find the sound I like...and with the $ I save maybe get a FIPK....