Looking for a unicorn muffler.

[bovey]

I'm trying to keep my truck quiet. However, everything I'm doing to it makes is noisy. And noisy does not work in the city I call home.

No, moving is not an option.

I'm running a 427 LSX built by SDPC Raceshop, it makes 611 HP at 6100 RPM. Headers have been designed by Burns Stainless, triple step into 3.5 collectors. After that, it 's dual exhaust via twin Vibrant GESI cats and mufflers - all 3.5". Might side exit in front of the rear wheels, or just behind. Not exactly sure of design yet as I'm sorting out my fuel cell and dry sump oil tank location.

On my current 3" system, I've used 3" Flowmaster Delta 50s, and I'd like to be quieter.

Due to a large amount of engine setback, I may not have space for an "X" pipe.

Obviously, I'd rather not sacrifice power, but something with have to give.

Any thoughts or advice/brands on mufflers would be appreciated.

Thank you in advance.

[sheck44]

Ditch the Flowmasters ... Magnaflow, Borla would be a good place to start

Cheers
steve

[Protour_Pinto]

I wish that mufflers had a flow rating. I know its a tough thing because of engine size, and many other variables.

I plan on using a Bus Muffler on my truck, Im thinking it should flow well enough for a mild OG 500ci engine and keep it fairly quiet.

Have you thought about some OEM mufflers like on the newer Vettes, Mustangs and Hemis? I know some of the late model vettes have a vacuum operated valve that opens at higher RPMs.

[bovey]

Ditch the Flowmasters ... Magnaflow, Borla would be a good place to start Cheers steve

Thanks Steve. They are on my hit list. Thank you for the reco.



I wish that mufflers had a flow rating. I know its a tough thing because of engine size, and many other variables. I plan on using a Bus Muffler on my truck, Im thinking it should flow well enough for a mild OG 500ci engine and keep it fairly quiet.

Have you thought about some OEM mufflers like on the newer Vettes, Mustangs and Hemis? I know some of the late model vettes have a vacuum operated valve that opens at higher RPMs.

Interesting option. I looked up Vette mufflers and they are huge. I don't have a lot of space. However, while looking into this I found out that modding mufflers is actually a thing. Never thought of that option. People actually cut open mufflers and change them to suit their applications. Neat. Thanks again for your thoughts.

[Canon_Mutant]

Well, general rules you probably already know do apply. Size generally matters in this particular case. I put the largest Magnaflows I could fit behind my big block Olds in my 442 that are 5x11x22. I would have gone even larger but that is all that will fit. But, it has a really nice but mellow rumble at idle. Oh you can certainly hear it when your foot is in the fan but at highway speeds it will almost go quiet in the 1800-2200 rpm range the way I am geared.

What I do NOT know is what these huge diameter exhaust systems like yours add to this equation? I've got just 2 1/2 all the way back through high-flow Magnaflow Cats and I cannot begin to get the power I make to the ground . . . though my pro-touring transition mission I am on should be helping that significantly by this spring.

At least . . . that is the plan! :idea:

[HandOverFist]

I've seen it somewhere in print that a 2 into 1 w/collector system combined with a single specialty (large) muffler will quiet things down considerably while making more power throughout the rpm range.

[PRRC]

Try spin tech. We use them all the time in the shop.

[dirty rick]

Flow master 40 and 50 are aggressive sounding mufflers

Try a 70 series. http://www.flowmastermufflers.com/70-series/

[Dark Pursuit]

Dynatec Vt mufflers might be what you are looking for.

[TXsilverado]

Big straight through mufflers like stated. Magnaflow, borla, spintech...bigger the better. Quieter and better performing than flowmaster mufflers. Dual 3.5 is hard to tame down.

[camarodude87]

Magnaflow has always been the quite go to mufflers on ls1tech.

[sam 74]

Borla makes a good muffler and its quiet, i used the 16 inch XR1 on my 470 race motor and was able to use it on the street without getting a ticket for noise.

[Protour_Pinto]

Thanks Steve. They are on my hit list. Thank you for the reco.




Interesting option. I looked up Vette mufflers and they are huge. I don't have a lot of space. However, while looking into this I found out that modding mufflers is actually a thing. Never thought of that option. People actually cut open mufflers and change them to suit their applications. Neat. Thanks again for your thoughts.

Yeah, The vettes have some chunky mufflers, I have a set from a C6 in storage. They are 13"LX12"WX9"H. in the car they sit "Tall Ways" but I have cut the outlets off and rotated them in the past.

[bovey]

Hello everyone, thank you for your comments and suggestions. I'm currently speaking to Borla, Spintech and Magnaflow. Dynatek does not make a muffler over 3" so I am passing on them. Once I have all of the information, I will report back.

[Protour_Pinto]

Spintechs are good but run pretty hot.

[downl50]

I'm looking for something similar for a 580hp small block but 3" exhaust. I've been listening to Dynomax Super Turbos which are pretty inexpensive and quiet. Borla looks attractive but when you add in the resonators for their setup you're getting to $800 in just mufflers.

I've also heard Corsa is worth looking at. I had a hard time figuring out from Spin Tech's website what might make sense so prob worth the call.

I'll be interested to hear what you learn and go with!

[Charlie Brengun]

Perhaps adding more mufflers will make it a little less loud, something like dynomax race bullets near the headers and hooker aerochamers where your mufflers normally would be. Both are available in 3 1/2 inch.

[68sixspeed]

Also while it will lose a bit of hp, exhaust manifolds are quieter than headers. I'm surprised on a Vette how much louder headers alone are. Ls7 z06 manifolds have decent flow, only a 10-15hp loss on a 600hp motor.

As others mentioned ditch the flowmaster for a s-path turbo type muffler. I have magnaflow 3" on the camaro and they are good but not really quiet either. But the x/pipe magnaflow uses is a bit louder than a H-pipe too. An h-pipe will quiet a system a touch if you don't have a crossover. The old hooker super comp mufflers were quieter than the magnaflow.

[ilikeike]

I'm looking for something similar for a 580hp small block but 3" exhaust. I've been listening to Dynomax Super Turbos which are pretty inexpensive and quiet. Borla looks attractive but when you add in the resonators for their setup you're getting to $800 in just mufflers.

I've also heard Corsa is worth looking at. I had a hard time figuring out from Spin Tech's website what might make sense so prob worth the call.

I'll be interested to hear what you learn and go with!

My SBC 421 has similar HP (494 rwhp,before additional upgrades), Using 3" Magnaflow and a Pypes X pipe terminated at the axle.
It's pretty beastly sounding,I don't even think going over the axle would do much. But it sure sounds good when it's on the pipe.

[downl50]

Hello everyone, thank you for your comments and suggestions. I'm currently speaking to Borla, Spintech and Magnaflow. Dynatek does not make a muffler over 3" so I am passing on them. Once I have all of the information, I will report back.

Looking for something similar (550hp sbc, street driven Chevelle, looking for very quiet).

Suggestions from talking with the companies
Borla: XR1s with a second set of round mufflers after them. CrateMuffler will not handle over 450hp


Magnaflow
12289 is a 5x8x24inch muffler, sounds pretty good if it'll fit


SpinTech: XL Plus is 3x10x16. They also rec'd 3" to the muffler and then 2.5 out the back to reduce noise without much performance difference.


Interested to hear if anyone has experience fitting 2 sets or one of these larger mufflers.

[downl50]

Bovey, any progress on making your selection?

I'm down to Borla XS pro, Dynomax Hemi Turbo, Magnaflow (either 12289 or the wide/shorter model), Spintech 3000XL plus. These seem to have all gotten votes of lower pitched with no drone. I don't know about overall db level though.

I came across old post from Chevelles.com -- not sure what to make of the supporting 1500hp claim but some interesting tips that I'm planning to try including the Car Chemistry inserts and doing 3" to the mufflers then 2.5" to tips. I have 1 7/8 primaries with 3.5" collector made by Lemons.


"(1966 Chevelle)
Starting at headers:
Car Chemistry 3-disc collector inserts

(Ultraflow #24215 2.5 12" Bullet) <---No room on Camaro

Dr Gas X-Pipe 2.5 in/out

Ultraflow #17236 2.5 Mufflers 24" case

2.25 Tailpipes

Quiet is an understatement. Pure cam & header "ping" inside.

Full-throttle is more like an RPM-based ever-deepening
"tuned" sound, somewhere between a NASCAR & an F1 exhaust.

This particular combination is the final culmination of 30-plus
years of experimentation & a lifelong interest in IC gas flow &
exhaust systems. This system could support a 1500 hp/2000
cfm engine w/o any appreciable difference vs. an open exhaust.

It represents TR's maxim "Walk softly and carry a big stick" well.

There is probably more mythology & misunderstanding
regarding exhaust system design & performance than
any other choices to be made in the car's build. What
works versus what doesn't falls way behind what anyone
thinks "sounds best" on most exhaust system decisions.

HTH someone!!"

[bovey]

Bovey, any progress on making your selection?

Yes, sorry for the delay. I've had a hard week. Before we discuss my findings, but we need to address this 1500 HP Chevelle below.




I came across old post from Chevelles.com -- not sure what to make of the supporting 1500hp claim but some interesting tips that I'm planning to try including the Car Chemistry inserts and doing 3" to the mufflers then 2.5" to tips. I have 1 7/8 primaries with 3.5" collector made by Lemons.


"(1966 Chevelle)
Starting at headers:
Car Chemistry 3-disc collector inserts

(Ultraflow #24215 2.5 12" Bullet) <---No room on Camaro

Dr Gas X-Pipe 2.5 in/out

Ultraflow #17236 2.5 Mufflers 24" case

2.25 Tailpipes

Quiet is an understatement. Pure cam & header "ping" inside.

Full-throttle is more like an RPM-based ever-deepening
"tuned" sound, somewhere between a NASCAR & an F1 exhaust.

This particular combination is the final culmination of 30-plus
years of experimentation & a lifelong interest in IC gas flow &
exhaust systems. This system could support a 1500 hp/2000
cfm engine w/o any appreciable difference vs. an open exhaust.

It represents TR's maxim "Walk softly and carry a big stick" well.

So this Chevelle guy claims he put 1500 hp through 2.25" tailpipes? I need a dyno video. Or is it a 3000 hp system chocked down to 1500 hp due to the exhaust? ;)

In all seriousness, I did have Burns Stainless run numbers on my engine. I gave them exact details, including how I plan to use the truck and what part of the power band I wanted to control with the exhaust. Burns came back with a header design and a reco on running dual 3" or 3.5", but based on the rpm levels I'll operate at they suggested the 3.5" is the way to go. It also gives me room to make more power and be able to use the same exhaust.

Another thing Burns said: "For a successful exhaust design it should always get bigger as you build from the head to the tailpipe". The Chevelle guy does the complete opposite. Burns is not just anyone, they design headers for the Pratt and Millers Corvette Race Teams. I'm willing to believe there are different ways to do things, but if I was building a 1500HP car, I'd need more proof than a forum post for that set-up. Thanks for sharing this, such a curious claim!

Thank you to everyone with their responses. Appreciated very much.

I'll be back with my research. Sleep. Now. Long week.

[HandOverFist]

Yes, sorry for the delay. I've had a hard week. Before we discuss my findings, but we need to address this 1500 HP Chevelle below.





So this Chevelle guy claims he put 1500 hp through 2.25" tailpipes? I need a dyno video. Or is it a 3000 hp system chocked down to 1500 hp due to the exhaust? ;)

In all seriousness, I did have Burns Stainless run numbers on my engine. I gave them exact details, including how I plan to use the truck and what part of the power band I wanted to control with the exhaust. Burns came back with a header design and a reco on running dual 3" or 3.5", but based on the rpm levels I'll operate at they suggested the 3.5" is the way to go. It also gives me room to make more power and be able to use the same exhaust.

Another thing Burns said: "For a successful exhaust design it should always get bigger as you build from the head to the tailpipe". The Chevelle guy does the complete opposite. Burns is not just anyone, they design headers for the Pratt and Millers Corvette Race Teams. I'm willing to believe there are different ways to do things, but if I was building a 1500HP car, I'd need more proof than a forum post for that set-up. Thanks for sharing this, such a curious claim!

Thank you to everyone with their responses. Appreciated very much.

I'll be back with my research. Sleep. Now. Long week.

The way I read it is he states it "could" support that level...not what it currently is.

[bovey]

The way I read it is he states it "could" support that level...not what it currently is.

"could" excellent point.

[downl50]

Agree, I don't really know what "supports 1500hp" means. My read from a few dyno tests done by magazines is that anything north of 500hp is at least somewhat restricted by a 2.5" system. I have had several manufacturers suggest doing 3" to the muffler and 2.5" tips.

I'm going to do this with the Pypes kit with tips out the back and run the largest magnaflow I can fit -- need to measure but several people claim they've fit the 5x8x24". I'm going to try to hold off on a second set of mufflers but now seen several people adding a small round muffler to reduce volume.

[TXsilverado]

don't read too deep into internet racers/gurus. pay attention to the guys running fastest and setting records. NONE of those guys are running 2.5" exhaust. period.

if your car is N/A, dual 3" will more than likely take care of your needs

big nitrous (not a dinky 200 shot) or higher boost level blower cars can start looking at larger than 3" duals. and of course, it all depends on what you're wanting to do with the car.

[CSG]

FWIW I have made 680rw on a mustang dyno with dual 2.75" factory GT500 mufflers. They were not overly quiet but not terrible. This was a forced induction car though.

[CarlC]

Here's some interesting info https://www.youtube.com/watch?v=_PVXvHkr-Vs&t=762s

It compares 2.5" vs. 3" in an engine with likely a very similar airflow requirement.

I just finished putting a full 3" exhaust with a Magnaflow X-over and dual 18" long Magnaflow mufflers in the Camaro. It's 10lbs of stuff in a 10lb hole, but is surprisingly quiet. It does, however, make all the right noises at WOT.

[CSG]

That video shows Magnaflow mufflers. I am pretty sure that atleast at one time that series was not 3" on the inside.
I picked up 50rw on a turbo car by going up to 3" from 2.75" but I also changed the type of muffler. This was an 900 hp or so car. Turbo cars are certainly different though so I don't know if it even relates...

[bovey]

I've spoken to Burns Stainless and recently Vibrant Performance stopped in the see my build after seeing it on Facebook. Both of these companies say versions of the same thing. There are a large number of variables when building exhaust. NA vs. forced? Use of engine, road race vs. drag vs. etc? Where you want to help the engine make power? Pure street car vs. dual purpose car vs. track only? Space and and the actual space you have can dictate your options too. You really need to weigh the options based on your build and use needs.

Headers for example, depending on the use, have room to be flexible with their design. If you are a pro team looking for squeeze every ounce of power of of an engine - then NO, you need to get really harsh on the build specs. Forced induction guys just make it fit and they can because ram a crap load of air into the engine, NA cars need a little more care, but again, unless you are going all out pro level - you have wiggle room.

Also, too CarlC's point, I'm after regular driving noise, just to cut down on fatigue - WOT is WOT.


All of this being said, here is what I found out. I have called and spoken to the tech lines of Borla, Spintech, and Magnaflow. Everyone was nice and took the time to talk.

1) Borla recommends using their XR1 - 40946
137248
3.5"/3.5" out - 4.25" x 8" x 16" case size - stainless steel. I've listened to a few on youtube and like them, that being said the videos I found did not have the engine mods I do.


2)Spintech. I can't recall the guys name, but I have the feeling he owned the place. Very nice, super willing to talk. He wants me to run 3", so much so he would not give me part numbers for 3.5", he said I did not need 3.5". Even after I explained to him that I had an company work out the flow rates for my engine, he seemed convinced 3" was sufficient and their street cars all use 3". Again, I explained my truck is going to see some fairly harsh competition use and prolonged rpms, he stuck to his 3" street car POV.

He recommended these two mufflers:

A) Superstock 1000XP - 4" x 9.5" x 14-15" case size
137247

B) XR90 - centre in/side exit (think AAR Cuda) 4" x 10.5" x 18"-20" case size
137249

For stainless, Spintech requires a 2 week build lead time. They are built to order.

3) Maganaflow recommends their 12909
137246

3.5"in/3.5" out - 5" x 11" x 22" case size. Magnaflow uses packing to aid noise reduction, unlike the others. So their sound will change over time. Again, I like the sound of these.

In general terms the bigger the case, the more sound they control. This gives the Spinach XR90 and MF the edge. Based on the videos, and a discussion with my guys at my local speed shop (Performance Improvements), I'm leaning towards Borla. I'd kinda like the try them all. As for cost, they are all in the same-ish ballpark.

The headers are done, I'm just looking into heat coatings as I've pushed the engine back about 18" and the headers are beside the footwell now. We've just torn the truck back down again to paint the firewall and properly assemble the 427/OS Giken clutch/Tranzilla t56 and stuff it back in. Looking forward to firing this stuff up.

137250

I'll come back with an update when things happen.

[CSG]

I had spintech on my road race car and they were the loudest muffler I have ever owned (size for size)

[downl50]

I ended up with 2.5" all the way out the back with magnaflow oval 18" (largest I could fit). Great sound quality, little louder than my ideal so may try to add a second set or maybe even cats. This is with a 580hp 427.

[cdrod]

... I put the largest Magnaflows I could fit behind my big block Olds in my 442 that are 5x11x22. ...

You got a 22" long muffler to fit under a 442? Was that an A-body or a G-body? Were you running tailpipe or dumping in front of the axle? Did the exhaust hang down lower than a stock system? I'm building a '72 442 convertible and I don't want it to be too loud. I'm leaning toward a Dynomax Super Turbo #17749 but it's 20" long, the stock muffler was only 17" long. I want the exhaust system to tuck up nicely under the car; don't want it hanging down where you can see it. Thanks for sharing your experience.
Rodney

[rennat_2006]

Hooker maxflow or maximum flow mufflers. You can tell it isnt stock at idle, good sound while accelerating normally, no drone and quiet cruise, and gets loud when you step into throttle real hard.

They come in 3.5" sizes.

There is a sound level(db ) and horsepower/tq test of like 15 different mufflers all on the same car all dyno'ed and db'ed floating around on the internet somewhere, i will try to find it and post a link. These max flow mufflers were in like the top 3 in both hp and sound levels with #1 being the most quiet.

They are my go to muffler now for just about anything, drone drives me absolutely crazy and constantly having to yell to talk to the passenger next to ya is no fun either.

[USAZR1]

You got a 22" long muffler to fit under a 442? Was that an A-body or a G-body? Were you running tailpipe or dumping in front of the axle? Did the exhaust hang down lower than a stock system? I'm building a '72 442 convertible and I don't want it to be too loud. I'm leaning toward a Dynomax Super Turbo #17749 but it's 20" long, the stock muffler was only 17" long. I want the exhaust system to tuck up nicely under the car; don't want it hanging down where you can see it. Thanks for sharing your experience.
Rodney

I'm going to install a pair of those 20" Dynamax mufflers on my 70 Elco. It's running a 383" sbc that probably makes 450hp. The #17749's are quiet and have virtually no resonance.
I've got room for the 22" Dynomax Turbo mufflers but the price is quite a bit more.

[Jeff70]

Several of Mark Stielow's cars are running the Borla XR1 with 800+ Hp. I've heard most of them in person and must say very mild at idle and under normal driving conditions until WOT then it sounds like WAR.