It's getting harder to be a successful aftermarket exhaust company. The days of selling on the promise of horsepower may be nearing an end. Exhaust companies are now facing tough competition from an unlikely source - the automakers. As companies like Ford strive to increase fuel economy they are making significant changes in engine technology and efficiency. With advancements such as variable valve timing and high efficiency cylinder heads, the combustion chambers don't need nearly as much scavenging - the effect of the exhaust creating negative pressure to draw out spent combustion gasses from the cylinder. Scavenging was something exhaust companies leveraged to achieve their power claims. To add salt to the wounds, the aftermarket mufflers often increase drone to levels unacceptable to the owner. This has become particularly true as more and more new vehicles come with mufflers mounted right behind the rear bumper, with no discernible tailpipe length to reduce the frequencies that cause drone.

Kevin McLelland, Research Manager at Flowmaster Mufflers, identified this threat long ago, and has been shouting it from the proverbial rooftops at Flowmaster ever since. "Until recently the formula was simple. However with new cars it is very tough to differentiate your product. We don't want to be in a position where we are selling on sound alone, because that is what every exhaust company does." That is a remarkable statement coming from Flowmaster, which has arguably developed the most marketable sound of any product in any industry.

Creating a competitive edge.
Flowmaster realizes that while their marketing edge is 'that sound', their competitive edge is being at the forefront of exhaust technology. Flowmaster performs a lot of research, so much so that it's R&D facility is larger than the manufacturing and administrative buildings of many of its competitors.

The research varies as vastly as Flowmasters product line. One week the focus might be on improving their end-caps to reduce stress fracture points on their off-road mufflers. (Flowmaster has developed their own vibration jig to hyper-simulate the stress a muffler goes through while under a car.) While the next week the research might be more theoretical - Flowmaster is well known for its studies on how consumers respond to exhaust sound.

More recently Flowmaster has been studying the effects of its mufflers on fuel economy. Most companies perform no such testing and take the rudimentary approach of: If the muffler fits then it is ready for production.

Fuel Economy Testing
One such fuel economy test was performed on Flowmasters new V6 Mustang "American Thunder" muffler. It's a single muffler that looks externally similar to the GT mufflers but is quite different on the inside. Most companies are basically putting a dash-one behind their GT muffler part number and calling it a Mustang V6 muffler. However, they don't sound quite right and the drone is very noticeable. "V6 engines are very harsh due to the firing order. You really have to take muffler design into consideration to offset the firing pulse, " explains McClelland. Flowmasters V6 muffler has a resonator tuned to achieve just this.

Cutaway of a factory "three-pass" muffler as found on the 2005-2007 V6 Mustang. Notice the 2.5" inlet pipe immediately restricts to 2". This results in a quieter exhaust note as result of increased backpressure.	Cutaway of the Mustang V6 muffler, a modified 60-series design. The inlet (left) leads into a power chamber. The DeltaFlow plates split the sound waves. The second chamber is the balance chamber. The sound waves here are met with sound waves in the Resonance Chamber, creating a cancellation effect. This design keeps backpressure to a minimum - below 2psi.
Kevin set up a 6.8 mile city loop and a 10.6 mile highway loop around Flowmaster's headquarters in Santa Rosa, CA, modeled after the Federal fuel economy testing procedures. Per procedure the loop must be driven several times obeying all posted speed limits. The average speed must be within a certain range for each run for the tests to be acceptable.	Kevin drove the 2006 V6 Mustang around the Santa Rosa,CA city loop, the average speeds were 25.28, 25.47 and 25.02 miles per hour. A drive that yielded 28 mph was thrown out. For the highway stretch of 10.2 miles, the cruise control is set to 65mph. The repeatability was between 66.2 and 66.9 mph.