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Giant Muffler Comparison - Detailed Test Results

What we found when we put the mufflers to the test.

By Julian Edgar and Graham Pring, Pics by Julian Edgar

Click on pics to view larger images


The Baselines

So that comparison can be made with the results gained with having no muffler at all, here are the baselines:

Straight 2 inch tube flow on flowbench: 353 cfm
Suzuki static noise, cat but no muffler: 102 dB(A)
Cobra static noise one muffler and no cat: 99 dB(A)
Seca static noise, cat but no muffler: 100 dB(A)
Seca full-load peak, cat but no muffler: 122 dB(A)

Straight Thru Designs

Muffler Orientation Flow Suzuki static noise Cobra static noise Seca static noise Seca full-load noise
Genie Resonator - 378 cfm 98 dB(A) 95 dB(A) 95 dB(A) 109 dB(A)
Genie Tornado centre in 362 cfm 91.5 dB(A) 90 dB(A) 91 dB(A) 108 dB(A)
offset in 359 cfm 91 dB(A) 90 dB(A) 89 dB(A) 107 dB(A)
Exhaust Technology (M) 14614 - 382 cfm 93 dB(A) 94 dB(A) 94 dB(A) 109 dB(A)
Exhaust Technology ?tube? - 347 cfm 100 dB(A) 98.5 dB(A) 98.5 dB(A) 112 dB(A)
Walker 20627 Resonator vents forward 281 cfm 100 dB(A) 97.5 dB(A) 95 dB(A) 116 dB(A)
vents rear 308 cfm 101 dB(A) 98 dB(A) 95 dB(A) 116 dB(A).
Walker PF41 Resonator vents forward 401 cfm 102.5 dB(A) 100 dB(A) 98 dB(A) 120.5 dB(A)
vents rear 395 cfm 101.5 dB(A) 98.5 dB(A) 95 dB(A) 119 dB(A)

Click for larger image
The best straight through muffler tested here is the Genie Tornado. It has a flowbench-verified flow figure as good as that of an empty pipe, and noise reductions as high as 18dB(A). Its stainless steel construction is very durable, although its higher price reflects both its performance and construction. It also has a pleasing sound.

Click for larger image
Second place goes to the Exhaust Technology M 14614, which is more compact in width than the Genie Tornado. This muffler actually outflowed the Genie, but was measurably noisier on each of the test cars.

Click for larger image
In third place is the Genie stainless steel resonator. It has excellent flow and gives a competent noise reduction, especially considering its compact size. Sound quality was fine.

Tri-Flow (Reverse Flow) Designs

Muffler Orientation Flow Suzuki static noise Cobra static noise Seca static noise Seca full-load noise
Genie Turbo centre in 252 cfm 87 dB(A) 88 dB(A) 89 dB(A) 107 dB(A)
offset in 252 cfm 87.5 dB(A) 88 dB(A) 89 dB(A) 107.5 dB(A)
Berklee BM482 centre in 194 cfm 90 dB(A) 90 dB(A) 85 dB(A) 105.5 dB(A)
offset in 188 cfm 88.5 dB(A) 89 dB(A) 89 dB(A) 106.5 dB(A)
Berklee BM480 centre in 155 cfm 88 dB(A) 92 dB(A) 82.5 dB(A) 82.5 dB(A)
offset in 129 cfm 87.5 dB(A) 85 dB(A) 84 dB(A) 84 dB(A)
Walker 17730 Super Turbo centre in 259 cfm 89 dB(A) 88.5 dB(A) 92 dB(A) 107 dB(A)
offset in 252 cfm 91 dB(A) 90.5 dB(A) 93 dB(A) 107 dB(A)
Walker PF29 centre in 217 cfm 88 88 91 106
offset in 217 cfm 89 88.5 88 106
Walker DM8X4 14002 solid tube 241 cfm 91 dB(A) 88 dB(A) 88.5 dB(A) 106 dB(A)
vented tube 239 cfm 88 dB(A) 88 dB(A) 88 dB(A) 106.5 dB(A)

Click for larger image
The best tri-flow (reverse flow or ?turbo?) muffler tested here is the Genie Turbo. It mixes amongst the best flowbench results with superior noise reduction over the other high-flowing mufflers. Another stainless steel design, it will have excellent longevity.

Click for larger image
In second place is the Walker DM8X4 14002 double offset mild steel design. (Note that there is another very similar Walker muffler that uses an offset/straight design. We tested it but this muffler did not perform as well as the double offset unit.) While the Walker DM8X4 14002 does not flow as well as the other Walker product - the Super Turbo - it has both demonstrably better noise reduction and sound quality.

Click for larger image
In third place is the Walker Super Turbo. It retains competent flow for this type of muffler and has adequate noise suppression, although its note is not as smooth as some of the other mufflers tested here.

Click for larger image
Special mention needs also to be made of the Berklee BM480, mounted with a 'centre in' orientation. While not a performance muffler (with a flow 38 per cent poorer than the winning Genie Turbo), the noise suppression of this muffler was staggeringly good. It dropped the full-load Seca's exhaust noise by no less than 39.5 dB(A)! It would be ideal as a temporary muffler fitted to get a car past a legal test...

Dog-Leg Designs

Muffler Orientation Flow Suzuki static noise Cobra static noise Seca static noise Seca full-load noise
Walker Lukey L0099 centre in 285 cfm 93 dB(A) 91 dB(A) 90 dB(A) 108 dB(A)
offset in 288 cfm 95.5 dB(A) 91.5 dB(A) 93.5 dB(A) 108 dB(A)
Berklee BM261 centre in 214 cfm 93 dB(A) 92 dB(A) 89 dB(A) 109 dB(A)
offset in 208 cfm 94 dB(A) 94 dB(A) 92.5 dB(A) 108.5 dB(A)
Click for larger image

The better flowing of the baffled designs is the Walker Lukey L0099. Of the two in this category of muffler, it has the better flow and slightly better noise suppression, together with an excellent quality sound - in fact, it's arguably the best sounding muffler of the lot.

Baffled Designs

Muffler Orientation Flow Suzuki static noise Cobra static noise Seca static noise Seca full-load noise
Berklee BB4413 short neck 207 cfm 85 dB(A) 87.5 dB(A) 83 dB(A) 105.5 dB(A)
long neck 175 cfm 86.5 dB(A) 90 dB(A) 83 dB(A) 106 dB(A)
Berklee BB3912 short neck 162 cfm 85 dB(A) 88 dB(A) 82 dB(A) 105 dB(A)
long neck 136 cfm 87 dB(A) 88 dB(A) 82 dB(A) 106 dB(A)
Manumatic UNI3480-2 - 210 cfm 85 dB(A) 85 dB(A) 86 dB(A) 107 dB(A)
Click for larger image

Because they all flow poorly, when dealing with baffled mufflers noise suppression is probably the most important criterion. If this is the case, the Berklee BB3912 has very good noise suppression, although accompanied by a raspy over-run.

Factory Mufflers

Muffler Flow Suzuki static noise Cobra static noise Seca static noise Seca full-load noise
Holden V6 Resonator (55mm) 311 cfm 96 dB(A) 93 dB(A) 93 dB(A) 118 dB(A)
Honda Prelude 214 cfm 88 dB(A) 88 dB(A) 84 dB(A) 106 dB(A)
Nissan 188 cfm 84 dB(A) 85 dB(A) 85 dB(A) 107 dB(A)
Mazda 929 207 cfm 84 dB(A) 88 dB(A) 80 dB(A) 106 dB(A)
VW Golf 4 cyl 246 cfm 87 dB(A) 88.5 dB(A) 85 dB(A) 107 dB(A)
Commodore Muffler 55mm 281 cfm 87.5 dB(A) 89.5 dB(A) 86.5 dB(A) 105.5 dB(A)
Click for larger image

As could be expected, the best flowing of the factory mufflers was a straight-thru resonator - the Holden unit - however, it was also relatively noisy. Of the other factory mufflers, the pictured Mazda 929 unit was the quietest.


Spreadsheet

So that you can examine and pore over all of the test information to your heart's content, the entire test results - including some mufflers (like the Pring Special!) not mentioned in the text are available here.

An Excel Spreadsheet is also available.

The Sounds

While the noise meter shows the weighted peak readings, lots of people are interested in the note - the quality of the sound - rather than just how loud the muffler is. So here's how each muffler sounded on the Seca, with the throttle blipped to 4000 rpm under no load. Remember, there's also a 2.5 inch cat fitted in the 'test' exhaust. Our descriptions are of course subjective - feel free to listen for yourself and perhaps disagree!

No muffler

Excruciatingly loud, many resonances with the application of power and very raspy on the over-run.
Hear it!
High Quality MP3
(File Size 36,066 bytes)
Low Quality 8 Bit WAV
(File Size 49,359 bytes)
Genie Resonator

Superb on over-run and deep, burbling power-on sound.
Hear it!
High Quality MP3
(File Size 38,780 bytes)
Low Quality 8 Bit WAV
(File Size 53,229 bytes)
Genie Tornado

Deep, smooth and muted sound on both power-up and the over-run.
Hear it!
High Quality MP3
(File Size 40,867 bytes)
Low Quality 8 Bit WAV
(File Size 56,009 bytes)
Exhaust Technology (M) 14614

Burbling four cylinder tone on power up and some rasp on over-run.
Hear it!
High Quality MP3
(File Size 36,897 bytes)
Low Quality 8 Bit WAV
(File Size 50,787 bytes)
Exhaust Technology "tube"

Excellent on over-run with some deep burble with power-on.
Hear it!
High Quality MP3
(File Size 52,148 bytes)
Low Quality 8 Bit WAV
(File Size 71,661 bytes)
Walker 20627 Resonator

Very four cylinder-ish burble with crackly over-run.
Hear it!
High Quality MP3
(File Size 39,823 bytes)
Low Quality 8 Bit WAV
(File Size 54,780 bytes)
Walker PF41 Resonator

Loud and raspy on both power-up and over-run.
Hear it!
High Quality MP3
(File Size 46,507 bytes)
Low Quality 8 Bit WAV
(File Size 64,025 bytes)
Genie Turbo

Smoother, mellow burble on application of power, some rasp on over-run.
Hear it!
High Quality MP3
(File Size 40,028 bytes)
Low Quality 8 Bit WAV
(File Size 55,087 bytes)
Berklee BM482

Deep mellow sound on power application, slightly less raspy on the over-run than typical.
Hear it!
High Quality MP3
(File Size 44,002 bytes)
Low Quality 8 Bit WAV
(File Size 60,309 bytes)
Berklee BM480

Hollow, high-pitched power-on sound and moderately raspy over-run.
Hear it!
High Quality MP3
(File Size 44,215 bytes)
Low Quality 8 Bit WAV
(File Size 60,616 bytes)
Walker 17730 Super Turbo

Burbly on-power sound very similar also on over-run.
Hear it!
High Quality MP3
(File Size 40,872 bytes)
Low Quality 8 Bit WAV
(File Size 56,009 bytes)
Walker DM8X4 14002

Deep and restrained on both power-up and over-run.
Hear it!
High Quality MP3
(File Size 34,178 bytes)
Low Quality 8 Bit WAV
(File Size 46,794 bytes)
Walker PF29

Higher pitched burble on power application and very raspy on over-run.
Hear it!
High Quality MP3
(File Size 33,134 bytes)
Low Quality 8 Bit WAV
(File Size 45,566 bytes)
Walker Lukey L0099

Deep on-power sound and superbly quietened over-run crackle.
Hear it!
High Quality MP3
(File Size 45,888 bytes)
Low Quality 8 Bit WAV
(File Size 63,055 bytes)
Berklee BM261

Deep 'four cylinder-ish' burble but very restrained over-run crackle.
Hear it!
High Quality MP3
(File Size 46,096 bytes)
Low Quality 8 Bit WAV
(File Size 63,296 bytes)
Berklee BB4413

Deeper burble on power, raspy on over-run.
Hear it!
High Quality MP3
(File Size 44,421 bytes)
Low Quality 8 Bit WAV
(File Size 60,923 bytes)
Berklee BB3912

Very subdued and smooth on power application, raspy loud over-run.
Hear it!
High Quality MP3
(File Size 46,931 bytes)
Low Quality 8 Bit WAV
(File Size 64,609 bytes)
Manumatic UNI3480-2

Deep and hollow sound on power, typical over-run rasp.
Hear it!
High Quality MP3
(File Size 44,629 bytes)
Low Quality 8 Bit WAV
(File Size 61,230 bytes)
Holden V6 Resonator (55mm)

Very raspy on over-run and power-up.
Hear it!
High Quality MP3
(File Size 36,904 bytes)
Low Quality 8 Bit WAV
(File Size 50,787 bytes)
Honda Prelude

Hollow sounding, high-pitched and raspy on both power-up and over-run.
Hear it!
High Quality MP3
(File Size 42,956 bytes)
Low Quality 8 Bit WAV
(File Size 59,080 bytes)
Nissan

High-pitched but restrained and smooth on power-up, some rasp on over-run.
Hear it!
High Quality MP3
(File Size 38,149 bytes)
Low Quality 8 Bit WAV
(File Size 52,323 bytes)
Mazda 929

Restrained but high-pitched on both power and over-run.
Hear it!
High Quality MP3
(File Size 34,596 bytes)
Low Quality 8 Bit WAV
(File Size 47,409 bytes)
VW Golf 4 cyl

Tinny sounding on both power and overun. The worst sounding muffler here!
Hear it!
High Quality MP3
(File Size 35,009 bytes)
Low Quality 8 Bit WAV
(File Size 48,023 bytes)
Commodore Muffler 55mm

Very subdued on power application but distinctively raspy on over-run.
Hear it!
High Quality MP3
(File Size 39,613 bytes)
Low Quality 8 Bit WAV
(File Size 54,473 bytes)
Giant Muffler Comparison - The Mufflers!
Giant Muffler Comparison - Testing Procedures
Giant Muffler Comparison - Summary of Results
Random Bits
1. Old Versus New

We also tested an old and worn high-kilometre Walker Super Turbo to see how it compared with the brand new unit. Here are the results:

Muffler Orientation Flow Suzuki static noise Cobra static noise Seca static noise Seca full-load noise
New Walker Super Turbo centre in 259 cfm 91 dB(A) 88 dB(A) 88.5 dB(A) 106 dB(A)
offset in 252 cfm 88 dB(A) 88 dB(A) 88 dB(A) 106.5 dB(A)
Old Walker Super Turbo centre in 262 cfm 90 dB(A) 88 dB(A) 89 dB(A) 106 dB(A)
offset in 246 cfm 90 dB(A) 88.5 dB(A) 89 dB(A) 106 dB(A)

These test figures show that there was very little change in performance between the old and the new. However, when each muffler was actually fitted to a car being used daily, the old Walker developed a drone.

2. Back-Pressures

Exhaust back-pressure measurements on both the Seca and Sierra were taken on the dyno, in each case with the probe being placed before the cat converter. When the car was fitted with just the 'test' exhaust complete with its 2.5 inch cat (395 cfm at 20 inches of water on the flowbench), the Seca developed a peak back-pressure of 1.2 psi. With the Exhaust Technology M14614 straight through muffler fitted as well (382 cfm), the exhaust back-pressure rose a little to 1.3 psi. But when a poorly flowing muffler like the Berklee BM480 (155 cfm) was fitted, exhaust back-pressure rocketed to 4.2 psi! In separate dyno testing of the Suzuki SJ50, this particular muffler also gave the highest back-pressure reading, peaking at 1.4 psi. Interestingly, all of the other mufflers gave effectively zero back-pressure readings on the 32kW-at-the-wheels Suzy.

3. More on Back-Pressures

You'd expect to see a strong relationship between the muffler flow measured on the bench and the back-pressures developed by the Seca: ie the poorer the flow, the higher the back-pressure. And as you can see from the graph, the inverse relationship certainly exists...

4. Testing Times
  • During the Suzuki dyno testing (mentioned above) it took at least 10 full-load power runs to get the dyno up to temperature and/or the car up to stable conditions to allow repeatable power figures. The eddy current dyno retarder temp stabilised at 100 to 110 degrees C.
  • Noise at wide open throttle measured about 6 metres from rear of Suzuki varied between 93 and 95 dB(A) with any of the mufflers fitted. There was a difference of only 1 dB(A) between a cold and hot exhaust/muffler system. Measured noise decreased by one d(B)A with the bonnet up.
  • With the static noise testing of the Cobra it was found that levels varied by up to 4 dB(A) between a cold exhaust/muffler system and a hot system with the same muffler. The noise output went up as the heat in the system went up (The exhaust temperature was allowed to stabilise before noise testing was carried out!).
  • The Suzuki's dyno-recorded power output was identical for both the worse-flowing (Berklee BM480) and best-flowing (Genie resonator) mufflers!

Contact:

Exhaust Technology
08 8272 7500

Awesome Automotive
08 8277 3927

F&M Cylinder Heads
08 8294 2515

Morphett Vale Exhausts
08 8384 6400

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