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) |
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.
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.
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) |
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.
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.
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.
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) |
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) |
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) |
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. |
|
Genie Resonator
Superb on over-run and deep, burbling power-on sound. |
|
Genie Tornado
Deep, smooth and muted sound on both power-up and the over-run. |
|
Exhaust Technology (M) 14614
Burbling four cylinder tone on power up and some rasp on over-run. |
|
Exhaust Technology "tube"
Excellent on over-run with some deep burble with power-on. |
|
Walker 20627 Resonator
Very four cylinder-ish burble with crackly over-run. |
|
Walker PF41 Resonator
Loud and raspy on both power-up and over-run. |
|
Genie Turbo
Smoother, mellow burble on application of power, some rasp on over-run. |
|
Berklee BM482
Deep mellow sound on power application, slightly less raspy on the over-run than typical. |
|
Berklee BM480
Hollow, high-pitched power-on sound and moderately raspy over-run. |
|
Walker 17730 Super Turbo
Burbly on-power sound very similar also on over-run. |
|
Walker DM8X4 14002
Deep and restrained on both power-up and over-run. |
|
Walker PF29
Higher pitched burble on power application and very raspy on over-run. |
|
Walker Lukey L0099
Deep on-power sound and superbly quietened over-run crackle. |
|
Berklee BM261
Deep 'four cylinder-ish' burble but very restrained over-run crackle. |
|
Berklee BB4413
Deeper burble on power, raspy on over-run. |
|
Berklee BB3912
Very subdued and smooth on power application, raspy loud over-run. |
|
Manumatic UNI3480-2
Deep and hollow sound on power, typical over-run rasp. |
|
Holden V6 Resonator (55mm)
Very raspy on over-run and power-up. |
|
Honda Prelude
Hollow sounding, high-pitched and raspy on both power-up and over-run. |
|
Nissan
High-pitched but restrained and smooth on power-up, some rasp on over-run. |
|
Mazda 929
Restrained but high-pitched on both power and over-run. |
|
VW Golf 4 cyl
Tinny sounding on both power and overun. The worst sounding muffler here! |
|
Commodore Muffler 55mm
Very subdued on power application but distinctively raspy on over-run. |
|
Giant Muffler Comparison - The Mufflers!
Giant Muffler Comparison - Testing Procedures
Giant Muffler Comparison - Summary of Results
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Random Bits
1. Old Versus NewWe 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-PressuresExhaust 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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