The AutoSpeed muffler comparison tested no less than 22 mufflers, 17 of which were brand new aftermarket designs and 6 of which were used, factory mufflers. We included the used factory mufflers to help establish a baseline - if the standard mufflers were already better than the aftermarket designs, why"d you bother going aftermarket? We also decided to standardise on mufflers with pipe diameters around two inches. Why? There were a number of reasons. Firstly, co-author Graham Pring had already sourced a huge number of new mufflers in this size. He intended picking the best and using two of them (one each side) on his V8-powered Cobra replica. Another reason is that sourcing comparable factory mufflers is much easier in two-inch pipe, rather than 2.5, 3 or 4 inch!
But if you are interested in using mufflers with tube sizes larger than those tested, look carefully at the results of the different muffler types - ie the performance of straight-thru, versus tri-flow (ie reverse flow), versus baffled mufflers. These lessons in noise and flow will also hold true for larger versions of the same mufflers.
The descriptions of the mufflers that follow are based on an external examination only - the exception is the Holden muffler that was cut open. Dimensions and masses are approximate.
Straight Thru Designs
We have defined a straight-thru design as having a single perforated pipe connecting the inlet to the inlet in a straight line. Note that in the case of the Exhaust Technology "tube", an expansion chamber is also positioned mid-way through the muffler.
Straight-through stainless steel absorption muffler. Round hole perforated tubing with stainless steel wool absorption material, with welded seams and polished. Dimensions: 30x13cm Mass: 2.5kg
Straight-through absorption stainless steel muffler. Round hole internal tubing with stainless steel wool plus other absorption material. Welded seams and polished. Centre / offset ends. Dimensions: 36x11x24cm Mass: 4.7kg
Exhaust Technology (M) 14614
Straight-through stainless steel absorption muffler. Round holes for full length. Larger bore internal tubing. Welded seams and polished. Dimensions: 36x15 Mass: 4.5kg
Exhaust Technology "tube"
Straight-through absorption mild steel muffler with round holes. Expansion chamber in centre of tube. Welded seams. Dimensions: 44x9cm Mass: 2.5kg
Walker 20627 Resonator
Straight-through mild steel absorption muffler. Directional inward punched louvres with absorption material. Welded seams. Dimensions: 28x9cm Mass: 1.8kg
Walker PF41 Resonator
Straight-through mild steel reflection style resonator with outward punching for half the tube length. Rolled seams. No absorption material. Dimensions: 25x10cm Mass: 1.4kg
Tri-Flow (Reverse Flow) Designs
A tri-flow (reverse flow or "turbo") muffler takes the exhaust gas on an S-shaped path through the muffler. The exhaust gas travels to one end of the muffler, is turned through 180 degrees and heads back to the first end. There, it is again turned through 180 degrees before it passes to the outlet. Tri-flow mufflers normally have three internal chambers.
Tri-flow reflection / absorption stainless steel muffler. Round hole internal tubing with stainless steel absorption material. Welded seams and polished. Dimensions: 36x11x25 Mass: 4.5kg
Tri-flow reflection mild steel muffler. One end inward directional punched louvres, other end solid tube. Rolled seams. Dimensions: 40x10x19cm Mass: 3.9kg
Tri-flow reflection mild steel muffler. Inward directional punched louvres with reduced diameter internal pipework to 42mm. Rolled seams. Dimensions: 40x10x19 Mass: 3.7kg
Walker 17730 Super Turbo
Tri-flow reflection / absorption mild steel muffler with tubes with holes punched outwards and rolled seams. Reduced internal diameter to 45mm. Absorption material around centre core. Dimensions: 36x9x20 Mass: 3.4kg
Walker DM8X4 14002
Tri-flow reflection mild steel muffler with one plain end tube and one end tube with holes punched outwards. No visible absorption material. Rolled seams. Offset / offset. Dimensions: 35x11x21 Mass: 3.4kg
Tri-flow reflection mild steel muffler with both end tubes featuring holes punched outwards. Reduced internal pipe sizes to 40mm. Rolled seams. Dimensions: 25x10cm Mass: 1.4kg
A dogleg muffler is a close cousin to the straight-through muffler, except the exhaust gas travels through an expansion chamber via a 'dogleg" path (ie two 90 degree changes in flow).
Walker Lukey L0099
Single flow reflection / absorption mild steel muffler with round hole perforated tubes. Centre expansion chamber. Absorption material around end sections. Rolled seams. Dimensions: 35x11x20 Mass: 3.5kg
Single flow reflection / absorption mild steel muffler. Middle expansion chamber with absorption material around both ends. Inwards directional punched holes with rolled seams. Dimensions: 40x10x19cm Mass: 3.6kg
We have placed all of the other muffler designs in this category. Baffled mufflers often have multiple compartments, several changes of gas direction, and work on both absorption and reflection principles.
Multiflow reflection mild steel muffler. One end tube inward-punched directional louvres, other end solid tube. Rolled seams. Dimensions: 49x11x26cm Mass: 4.9kg
Multiflow reflection mild steel muffler. One end tube inward punched directional louvres in reduced size tubing. Other end solid tube with reduced size internal tubing. Rolled seams. Dimensions: 49x11x26cm Mass: 4.9kg
Multiflow reflection mild steel muffler. One end tube inward punched directional louvres and other end with round hole tubing. Rolled seams. Dimensions: 49x11x26 Mass: 5kg
With the exception of the Holden designs, the inner workings of these mufflers aren't clear - we couldn't cut them all open! However, they use multiple baffles - other than the Holden resonator, none is a straight-thru design.
Holden Resonator (55mm)
Straight through absorption steel muffler. Fifty five millimetre tubing with outward-punched holes along one-third of the larger 60mm internal tubing. Rolled seams. Dimensions: 27x12x25cm Mass: 4kg
Probably from a late VTEC model. Dimensions: 35x25x29cm Mass: 5.2kg
Probably from a Pintara TRX. Dimensions: 45x15x31 Mass: 5kg
Dimensions: 50x20x23 Mass: 5.2kg
Four cylinder late model Golf. Dimensions: 45x13x24 Mass: 5kg
Commodore Muffler 55mm.
Multiflow reflection / absorption steel muffler. Four internal chambers with side tubes in main tubes. Two outer skins with a fine layer of fibreglass mat between the inner and outer skins. Rolled seams and spot welded skins. Dimensions: 27x12x25 Mass: 4kg
08 8272 7500
08 8277 3927
F&M Cylinder Heads
08 8294 2515
Morphett Vale Exhausts
08 8384 6400
Giant Muffler Comparison - Testing Procedures
Giant Muffler Comparison - Detailed Test Results
Giant Muffler Comparison - Summary of Results