Quieter Mufflers for Supercharged 5.0

oz · Jun 24, 2024

Greetings,
I have a '91 GT with a blown (Paxton/Novi 1220 SL) w/ a lot of go fast parts, including equal length Mac shorty headers, A MAC off-road H pipe, MAC mufflers and tail pipes... It's rev limited to 5100 and makes 488 hp there (stock bottom end so rev limited to keep it from 'expiring').
The problem is that when I get on it the sound it makes is just not acceptable. The volume is way too high and the actual sound is offensive. It's kind of a cracking sound... not a nice roar if you will...
Anyway, I plan to cut out the MAC mufflers and replace them - but I don't know what to replace them with... I don't want to restrict flow, but need to reduce the volume and, hopefully, make the sound a little nicer...
SUGGESTIONS?

Thanks!

Noobz347 · Jun 24, 2024

oz said:
It's rev limited to 5100 and makes 488 hp there

This [must] be a typo? Even the stock EEC runs to 6250

oz · Jun 24, 2024

Yea, set up aftermarket ignition with a lower RPM limit... I just checked and I shut it down at 5500....
Since the stock bottom end is 'only good for 400 hp' per most people, I figured I'd try to keep it together by limiting the revs (and therefore the boost & HP)... if the day comes I blow it up, I'll do it up right with a stout aftermarket shortblock and set the beast loose.

General karthief · Jun 24, 2024

2 1/2" pipes?

LILCBRA · Jun 24, 2024

Audio/video of the current sound you're talking about? And what exactly are you looking for - like almost stock quiet or "loud" without being obnoxious?

Assuming everything else is in good order, I'd try a pair of Flowmaster 50s. Kind of an apples to oranges comparison but I have a single in/dual out on my Ram and think it sounds great.

oz · Jun 24, 2024

I'll have to work on getting a video. Thanks for the suggestion (Flowmaster 50). I have Flowmasters on my other car and the sound is perfect - but it's not supercharged either...

I think it's 2-1/2" outlets... Not 3' I'm sure.

limp · Jun 24, 2024

I just went through this and from what I can find Walker quiet flow mufflers are about the quietest I could find.... All of these aftermarket mufflers are NOISY RUDE sounding to this " old " man......
Are you running any cats or other types of glass packs in your car?

oz · Jun 24, 2024

limp said:
I just went through this and from what I can find Walker quiet flow mufflers are about the quietest I could find.... All of these aftermarket mufflers are NOISY RUDE sounding to this " old " man......
Are you running any cats or other types of glass packs in your car?

No cats... off-road H-pipe behind equal length shorties.

limp · Jun 24, 2024

oz said:
No cats... off-road H-pipe behind equal length shorties.

You might need to do some resonators inline too... Depends on what your version of quieter is....
Problem with trying to quiet a Fox body exhaust systems is there is no room for a very large muffler at least in MY opinion...

Noobz347 · Jun 24, 2024

Converters would go a long way to quieting things down too.

oz · Jun 24, 2024

Noobz347 said:
Converters would go a long way to quieting things down too.

Probably true. Before I supercharged it, the sound level was what I wanted. Just some go fast parts, NA... I wouldn't want to put the stock cats back and doing it right with aftermarket cats may get pricy...

Noobz347 · Jun 24, 2024

MRT Engineering 1979-93 Mustang V8 MRT MaxFlow H-Pipe: HiFlow Cats - 93D000

MRT Engineering 1979-93 Mustang V8 MRT MaxFlow H-Pipe: HiFlow Cats - 93D000 The Mustang V8 MRT MaxFlow H-Pipe: HiFlow Cats has a loud, deep muscle car sound and is handcrafted in T304 Stainless Steel. This system includes 2.5" mandrel bent tube with T304

www.lethalperformance.com

oz · Jun 24, 2024

Noobz347 said:
MRT Engineering 1979-93 Mustang V8 MRT MaxFlow H-Pipe: HiFlow Cats - 93D000

MRT Engineering 1979-93 Mustang V8 MRT MaxFlow H-Pipe: HiFlow Cats - 93D000 The Mustang V8 MRT MaxFlow H-Pipe: HiFlow Cats has a loud, deep muscle car sound and is handcrafted in T304 Stainless Steel. This system includes 2.5" mandrel bent tube with T304

www.lethalperformance.com

Maybe I'll take the car over the MRT as they are about 3 miles from my home.

Noobz347 · Jun 24, 2024

Just roll up in there and say, "It's just too darn loud."

AeroCoupe · Jun 24, 2024

You can just get (2) Walker 15053 universal cats for about $200 and have them installed in your existing H-pipe. That is what I did on one of my BBK x-pipes to pass inspection in Texas. Exhaust was 1-5/8" equal length shorties, 2-1/2" x-pipe, 2-1/2" cat back with Flowmaster 42's. It was pretty loud without the cats and they did quiet it up a bit.

Amazon.com

rednotch · Jun 24, 2024

Hooker aero chambers if you want mild / quiet. but with what holleys been doing won't be long before they get discontinued. Alot of mufflers now are all the same China made stuff with different branding since flowmaster and other brand patent expired. Never heard any call Macs crackling though, chambers are probably rotted out if there not the stainless version.

Mustang5L5 · Jun 26, 2024

I ditched my Flowmaster 2-chambes for a set of Borla Pro XS mufflers in an attempt to quiet it down. For the most part it is quieter at idle but get loud when i step on the go pedal.

bwest · Jun 29, 2024

@oz - real question, how creative do you want to get w/ fabrication? Because of how little room there is under the car, packaging does require some creativity.

I second the hooker aerochambers - they are a good design. I had Mac mufflers/pro chamber/tail pipes, and I added cats as well. I did a lot of sound deadening in the interior, and it was still loud at times (HCI 302, no S/C) - was more the resonant frequency than the overall DB in the interior.

If it's an annoying freq at cruise, you have enough space to fab a 1/4 wave resonator to run along the mid pipe (math is required). Since you have a GT and the tail pipes are tucked, I would add a small diam resonator near the turn downs (12-14", 3.5-4" diam) as this will take care of the ringing that occurs in the long tail pipes. The lower bumper cover will hide it.

Lastly - pull the back seat out and stuff all the voids (there are a lot of them under the plastics as well) with denim insulation. It doesn't add much weight at all and it ads a lot of friction for longer sound waves. Killing air voids will also help with exhaust noise.

Pinellas50 · Jun 30, 2024

I ran Flowmaster 50s on my supercharged Ranger back in the day. It had a very deep rumble to it at idle and was not obnoxious under throttle. Definately quieter, less harsh, than the Flowmaster 40's I have had on my Foxbodies.

AeroCoupe · Jun 30, 2024

I do not think you are going to get a 23" long 50 series under a Fox Body. A 40 series is 13" long and there is wiggle room to get things lined up.

Quieter Mufflers for Supercharged 5.0

oz

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

oz

General karthief

wonder how much it would cost to ship you a pair

LILCBRA

I wish I didn't have all of these balls in the air

oz

limp

wrap a little cheese around it and its a done

oz

limp

wrap a little cheese around it and its a done

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

oz

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

MRT Engineering 1979-93 Mustang V8 MRT MaxFlow H-Pipe: HiFlow Cats - 93D000

oz

MRT Engineering 1979-93 Mustang V8 MRT MaxFlow H-Pipe: HiFlow Cats - 93D000

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

AeroCoupe

lube between the nut and the face. I know my lubes

rednotch

I'd like to remain having one chocolate starfish

Mustang5L5

That is…until I whipped out my Bissell

bwest

Member

Pinellas50

Active Member

AeroCoupe

lube between the nut and the face. I know my lubes

Similar threads

Quieter Mufflers for Supercharged 5.0

Stangnet Facilities Maint Tech... Er... Janitor

wonder how much it would cost to ship you a pair

I wish I didn't have all of these balls in the air

wrap a little cheese around it and its a done

wrap a little cheese around it and its a done

Stangnet Facilities Maint Tech... Er... Janitor

Stangnet Facilities Maint Tech... Er... Janitor

Stangnet Facilities Maint Tech... Er... Janitor

lube between the nut and the face. I know my lubes

I'd like to remain having one chocolate starfish

That is…until I whipped out my Bissell

Member

Active Member

lube between the nut and the face. I know my lubes

Similar threads

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