Quiet non-restrictive exhaust?

[jumpsoffrock]

My truck has a 402 and two new flowmasters(or something) with true dual exhaust.
I don't mind loud sports cars, but a truck IMO doesn't need to deafen you. I want this to be a comfortable truck I can drive for hours and not go deaf. I'm not trying to scare people.

Would the stock mufflers be too restrictive? Are there any options that sound essentially stock, but offer a little more performance?

Is there any horrendous reason I should absolutely not go to stock mufflers?

Thanks for any advice.

P.S. Part numbers for what I could/should order are appreciated.

[Mike C]

Walker SuperTurbo 20” case

[sick472]

I just put these on my 72 that sports a 350ish HP 400 (Pontiac motor)...

Dynomax Performance 17749 - Dynomax Super Turbo Mufflers, from Summit Racing (67$)...

https://www.summitracing.com/parts/WLK-17749

These 20" case length mufflers have the offset inlet and outlet and fit nicely where the General originally put them. They should compare very closely to the Walkers that Mike suggests. They are quiet and have great reviews for not being restrictive. The only complaint I have is that my exhaust system does have a short drone at about 2500 rpm in second gear (35 mph), not at highway speeds in third however. I think this is due to the pipes just off the manifold having to be 2-1/4" diameter to fit the manifolds. These pipes necks up to 2-1/2" within 2 feet of the motor and continue out the back at 2-1/2". I'm not very versed on exhaust systems, so the drone may be due to something else, but I doubt that it's on the mufflers. My duals are traditional and do not have the X or H pipe.

[jumpsoffrock]

^^^Dude you put a pontiac 400 in your chevy truck????

If so, BADASS

Thanks for the leads, guys.

[Steeveedee]

When I go to do my exhaust, it'll be a couple of '70s Cadillac mufflers. If one flows well enough for a 500 CI engine, two ought to be OK for a 400 CI engine. And when is the last time a stock Cadillac of that era "roared" by you with loud exhaust?

[SCOTI]

Originally Posted by sick472

I just put these on my 72 that sports a 350ish HP 400 (Pontiac motor)...

Dynomax Performance 17749 - Dynomax Super Turbo Mufflers, from Summit Racing (67$)...

https://www.summitracing.com/parts/WLK-17749

These 20" case length mufflers have the offset inlet and outlet and fit nicely where the General originally put them. They should compare very closely to the Walkers that Mike suggests. They are quiet and have great reviews for not being restrictive. The only complaint I have is that my exhaust system does have a short drone at about 2500 rpm in second gear (35 mph), not at highway speeds in third however. I think this is due to the pipes just off the manifold having to be 2-1/4" diameter to fit the manifolds. These pipes necks up to 2-1/2" within 2 feet of the motor and continue out the back at 2-1/2". I'm not very versed on exhaust systems, so the drone may be due to something else, but I doubt that it's on the mufflers. My duals are traditional and do not have the X or H pipe.

x2 on these mufflers.

I have the 3" versions on my Squarebody dually based off of internet research of muffler flow vs. sound testing. The testing was w/2.5" units but these mufflers tested almost @ the top spot for flow (straight-thru exhaust & a race only muffler ahead in flow) & were the most quiet after a stock muffler.

My set-up is:

461bbc w/true dual set-up.
1.75" full length car headers w/a 3" collector
3" head pipes to 3" H pipe into 3" In/Out mufflers
3" tubing out of the mufflers immediately reduces to 2.5" tubing
2.5" tail-pipes to the rear bumper

It's stockish quiet until my foot is into the throttle.
No drone.

[MikeB]

I've used Dynomax Super Turbos with the 20" case on at least two vehicles over the years. They're not a heck of a lot louder than OE-type mufflers, but they are less restrictive than Flowmasters according to tests done by David Vizard.

If you decide to use OE-type mufflers, keep in mind that they reduce sound by "restriction", so they typically "neck down" 1/2" or more internally. Good for quietness, but bad for power and efficiency. An option is to buy OE-type mufflers that are 1-2 sizes larger than your pipes, and connect them with adapters. For example, 2.5" mufflers on 2" to 2.25" pipes.

[jumpsoffrock]

Probably gonna go with dynomax super turbos, maybe 3" and have a new exhaust made? IDK might just stick them on as is and do full exhaust when pigs fly. lol

[jimijam00]

I recommend you get the 2.5 super turbos. 3.0 is probably too much if your 402 doesn't put out a lot of power. Besides, put a 2.5 on the left and a 3.0 on the right, the 2.5 will be quieter just about always.

[jumpsoffrock]

OK, that's great advice. I'll stick with 2.5"

[Richard]

If you like the Flowmaster sound just make sure to use the "big block" or 70 series muffler. Larger muffler pretty much always mean less sound. Have a single Flowmaster "Big block" 3" on my 94 get compliments all the time. Nice low tone, not to loud. Recently replaced it with the big block II as it had holes in it after 26 years. BB2 is a little narrower but same length. Friend put a 2.5" on his 2002 Chev truck and it sounds almost stock at idle to me. The 40 and 50 series were to loud then and are way to loud for me at this point in my life. Unless your are looking for every last hp. Really do not think muffler choice matters much on a DD. Looking at many muffler shootouts in the past I would guess the loss from running open exhaust on your set up to stock type mufflers would be less than 20 hp. See myself thinking about the Hooker Aero Chambers on my new build, I don't have a specific reason.

[MikeB]

I second the comment above about the 70 series mufflers being much quieter than 40 and 50 series. They are super expensive though!

[Big Kev-O]

Just about any 2.5 inch "turbo" muffler is going to give you plenty of flow while keeping things quiet. I installed some on a C3 Corvette and they have a nice deep idle although quiet, cruise without drone but show some power when you hit the pedal. There are even some affordable options in stainless that will work great. The difference in power between straight through, turbo & chambered mufflers are usually less than 10hp on anything under 500hp, typically around 5hp difference which is negligible. I found the Engine Masters muffler videos very informative. Check out Engine Masters "$40 Muffler Shootout" and "Cheap VS Expensive Mufflers" Episodes for some cool dyno tests and reviews. IIRC there are some nice quality stailness turbo style mufflers that are really affordable.


https://www.youtube.com/watch?v=Od3f_N-59Jo

https://www.hotrod.com/articles/engi...rs-episode-17/

[Mike C]

The Walker and the DynoMax same thing. Used to be called the Hemi Turbo but they must have run up against trademark issues.

You just don't need 3" exhaust for up to 500 hp. And it is a LOT more expensive and hard to run. 2.5" will be great.