Quiet exhaust system for 454

[focusedontheprize]

Currently waiting on powder coating for my wheels to finish up my wheel/tire project. While I am waiting, moving on to the next project.

The truck currently has a 7.4L 454 with long tube headers and Flowmasters. They exit right under the rear seats and the exhaust does not extend to the back unfortunately. The exhaust is WAY too loud for a daily driver for me and I will be changing it.

I am going back to stock exhaust manifolds and have been looking at the Flowmaster 70 Series vs. Flowmaster 50 Series Big Block mufflers. Has anyone had any experience with either of these?

[mongocanfly]

getting the pipes out the back will help a lot

[focusedontheprize]

Originally Posted by mongocanfly

getting the pipes out the back will help a lot

I would absolutely agree and am looking forward to that.

[sweetk30]

i run walker quiet flow s.s muffler now and its almost stock quiet .

[mongocanfly]

I've got a set of walkers as well...still in the box though

[Ziegelsteinfaust]

20 years ago almost I had a healthy 460 with 425hp/475tq roughly, and I used 4 Cherry Bomb long glass packs. Off the headers I used a Y fitting on each side. So each bank had two mufflers in parallel.

It was a absolute b-word to get set up with a H pipe, but most people thought I was rocking a nice 302. Guys who knew about cars usually said 351. So it fooled quite a few people.

Exhaust dampening is about exhaust volume, and the 4 mufflers provided a lot at a cheap price point.

So I would run 3" exhaust with the biggest packed muffler you can get. Or you can try the exhaust system I tried.

[blazer2007]

I had the same problem with a healthy 454 in my Blazer and couldn,t stand it with some nice stock style turbo mufflers exiting in fr. of rear tires.I made it full exhaust out the back and now I don,t mind driving it without everyone looking at me. I think best choice is full exhaust.

[LT7A]

I have the FM 50 on my Trans Am and it sounds fantastic. I'm not given to overstating things or giving myself props, but if you want to hear your motor, it sounds great. I had a FM 70 on a TBI truck and it was toooo quiet. I swapped it out to an FM 50 and it was perfect. Then I went to a high flow cat and it is now a little too loud. Probably you want the 70s. The 50s sound good but are pretty aggressive. If I was doing it, I'd run 50s with adding the pipes out the back. And just to confuse the issue and possibly discredit my whole post -- both vehicles are 350s not big blocks. In addition, they both have stock manifolds. I thought I'd chime in because I have experience with the two series you asked about. Tell us what you choose and how you like it in the end!

[dieseldawg142]

went thru 4 sets of mufflers for my 454 before it got to where i could stand it, but still enjoy the sound.
i too have long tube headers, but run 3" pipes.
started out with magnaflows, could barely hear myself, with a full exhaust.
switched to flowmaster 40's, cause they were on my small block '68 910 and sounded nice.
they turned out to be just as loud as the magna's.
next was a set of 50 series, still waaay too loud for me.
for the last few yrs now i been running big block 70's and i like them. mostly quiet when not into the throttle, but still barks when i step on it.

[focusedontheprize]

Originally Posted by dieseldawg142

went thru 4 sets of mufflers for my 454 before it got to where i could stand it, but still enjoy the sound.
i too have long tube headers, but run 3" pipes.
started out with magnaflows, could barely hear myself, with a full exhaust.
switched to flowmaster 40's, cause they were on my small block '68 910 and sounded nice.
they turned out to be just as loud as the magna's.
next was a set of 50 series, still waaay too loud for me.
for the last few yrs now i been running big block 70's and i like them. mostly quiet when not into the throttle, but still barks when i step on it.

Do you find the 70 Series to be closer to stock or still pretty aggressive? The objective for me is to keep the truck quiet (as this is my daily driver I leave my house very early in the morning and come home late at night) while still having great flow. Do you wish they were a little quieter or they are a good fit?

[dieseldawg142]

Originally Posted by focusedontheprize

Do you find the 70 Series to be closer to stock or still pretty aggressive? The objective for me is to keep the truck quiet (as this is my daily driver I leave my house very early in the morning and come home late at night) while still having great flow. Do you wish they were a little quieter or they are a good fit?

not close to stock sounding with headers and 3" pipes....and my 454 is not stock either, but it has a nice low rumble at idle (you can tell it's definitley not stock) and light throttle. if i lay into it, they get a little louder and sound really nice, but not obnoxious loud. after going threw a butt-load of muffs, quite happy with the 70's.
three inch pipes will make it a bit louder, and as my truck is a crew, the pipes are completely straight for about 6 or 7 feet to the rear axle, no corners to knock down the sound levels.
and the 50 series i ran were big blocks, and no way in hay were they quieter than the 70's.
i went with the 50's over the 70's first cause i wanted good flow and nice sound, but like i said, waaay loud...

[focusedontheprize]

Thanks everyone. I am leaning toward the Flowmaster 70 Series at the moment. It is a project that is next in line so I need to make a decision soon.

Just to be clear, when I am referring to the 50 series, Flowmaster makes a 50 Series Big Block that is quieter than the 70 series.

[44th Miss Inf]

If you want quiet and high flow, look into Donaldson mufflers

[JesseA422]

if u have motortrend, the latest episode of engine masters is a muffler shootout on the dyno with tons of different ones.

[DieselSJ]

I'm running a 3" to a huge Magnaflow and it is nice and quiet.

[kwmech]

Originally Posted by DieselSJ

I'm running a 3" to a huge Magnaflow and it is nice and quiet.

Perfect if it is a single 3'' pipe. Did the same on my flat bed and my pick-up, healthy sound without being annoying

[MalibuSSwagon]

2.5in pipes from the manifolds to a large Magnaflow 18" body, 24" overall muffler with single 3in out, exiting behind the rear wheel. Sounds awesome outside, but inside is quiet, no drone. Guys think it's a rowdy small block with headers, but really it's a stock 5.3L with manifolds lol. Love driving the truck with that exhaust.

[focusedontheprize]

Thanks everyone. Great responses and this has been really helpful.

[SCOTI]

I have Dynomax brand 'Super Turbos' under my dually.

The system is:
461/OE heads/RV cam
1 3/4" long tube car headers
Dual 3" head pipes w/a 3" 'H' pipe
3" in/out Dynomax turbo mufflers
2.5" tailpipe reducers
2.5" dual tailpipes that angle down/out @ the rear bumper brackets

All tubing after the headers is .065" wall SS. The 3>2.5" transition is immediately after exiting the mufflers which is right @ the back of the cab (CC). It's pretty quiet IMO. The big-block rumble/vibration can still cause car alarms to go off as you pass by if in an apartment complex or a corridor but my dually is 5" off the ground @ ride height

I bought these mufflers based on internet searches using the key words: 'best flowing/quietest mufflers' for my search. I came across multiple muffler comparison tests & reviewed common mufflers from the various tests. My priorities were the best flowing quiet mufflers.

Testing indicated the Super Turbos flowed as good as Borla race mufflers (which were the loudest/2nd to open headers) but were as quiet as OE mufflers (OE were listed as quietest w/the Dynomax as next in line). The testing results that I liked which seemed most informative was from a Pontiac magazine article & was based off of a warmed over 455 equipped wagon that had a 2 into 1 2.5" exhaust arrangement. 'Real world' testing results were on a drag strip which included the track times, sound levels @ cruise rpm & WOT. Since the Dynomax Super Turbos did so well vs. the other more popular brand-X mufflers in the 2.5" version I just got the same mufflers in the largest version I could find (length) in 3" in/out.

Pretty happy with the choice. I plan to get the same ones in 2.5" for my 64 if I don't like the ones it has (I had already acquired them for it before I did my research for the dually set-up).

[blazer2007]

Originally Posted by SCOTI

I have Dynomax brand 'Super Turbos' under my dually.

The system is:
461/OE heads/RV cam
1 3/4" long tube car headers
Dual 3" head pipes w/a 3" 'H' pipe
3" in/out Dynomax turbo mufflers
2.5" tailpipe reducers
2.5" dual tailpipes that angle down/out @ the rear bumper brackets

All tubing after the headers is .065" wall SS. The 3>2.5" transition is immediately after exiting the mufflers which is right @ the back of the cab (CC). It's pretty quiet IMO. The big-block rumble/vibration can still cause car alarms to go off as you pass by if in an apartment complex or a corridor but my dually is 5" off the ground @ ride height

I bought these mufflers based on internet searches using the key words: 'best flowing/quietest mufflers' for my search. I came across multiple muffler comparison tests & reviewed common mufflers from the various tests. My priorities were the best flowing quiet mufflers.

Testing indicated the Super Turbos flowed as good as Borla race mufflers (which were the loudest/2nd to open headers) but were as quiet as OE mufflers (OE were listed as quietest w/the Dynomax as next in line). The testing results that I liked which seemed most informative was from a Pontiac magazine article & was based off of a warmed over 455 equipped wagon that had a 2 into 1 2.5" exhaust arrangement. 'Real world' testing results were on a drag strip which included the track times, sound levels @ cruise rpm & WOT. Since the Dynomax Super Turbos did so well vs. the other more popular brand-X mufflers in the 2.5" version I just got the same mufflers in the largest version I could find (length) in 3" in/out.

Pretty happy with the choice. I plan to get the same ones in 2.5" for my 64 if I don't like the ones it has (I had already acquired them for it before I did my research for the dually set-up).

does it have that loud rapping noise when you step on the gas ? don,t care for that noise like some of the other mufflers

[SCOTI]

Originally Posted by blazer2007

does it have that loud rapping noise when you step on the gas ? don,t care for that noise like some of the other mufflers

The blapblapblapblapblapblapblap noise from almost every Charger, Challenger, 5.0, or Camaro? No, it doesn't sound like that. Sounds like a quiet turbo style muffler to me.

[tucsonjwt]

I have just stock mufflers on my 83 C20 454 and it is very quiet. The PO extended the pipes out the sides behind the rear wheel wells and it is still quiet. Pipes straight out the back is the standard configuration, but I like the side exit better and it is probably cheaper. My guess is that Midas did the exhaust since it has Midas mufflers, and the mufflers have no rust or leaks in the 17 years I have owned the truck. Of course, no salt in So. AZ desert.

[daddyjeep]

I am running dual 2 1/2" Cherry Bomb turbo mufflers behind my 454. My research said that they were about the only turbo style muffler that didn't drone at some point in the RPM range. My only complaint with them is that they could be a little louder. They exit in front of the rear tires and are really pretty quiet.

Lets see if this video link works.

https://drive.google.com/uc?id=1BQGi...zreMcklfRv1Xtc