Auto Service World
Feature   April 1, 2010   by Jim Anderton, Technical Editor

Double Down

Installing a DynoMax performance dual exhaust to turn a plain vanilla pickup into something special ... for you and your customer

Very few techs like exhaust work. It’s not especially profitable, interesting or satisfying for most consumers; but it doesn’t have to be that way. SSGM pushed back against exhaust boredom by testing an up-sell that’s not usually offered to the average vehicle owner — performance. The test machine was a base-model, short-box regular cab Ford F-150 pickup equipped with the 4.2L V-6 and 5-speed manual transmission. The OEM exhaust configuration for this vehicle is twin catalysts merging into a single collector feeding a single muffler and pipes. It’s conventional in the extreme with a very large muffler for excellent sound deadening at the expense of backpressure and weight. The upgrade was a DynoMax part number 39321 cat back performance system, which uses a dual outlet stainless steel muffler feeding dual pipes. It’s a totally different layout … how did it install?

What’s the verdict? The DynoMax 39321 dual exhaust kit installed easily in the F-150 test truck with no need for heat, hammering, grinding or bending to fit. The kit included all parts necessary for the job including clamps, which used the standard 9/16″ nut so no socket changes were necessary. A good design feature is the use of “cranked” or slightly offset stub tailpipes.

This allowed us to line up the tips evenly with the natural horizontal line of the step bumper, making the installation look perfect without bending pipes or re-jigging hangars.

And the sound? Much like a vintage Chris Craft speed boat, with a restrained, burbly rumble at idle and a throaty roar at WOT. The sweet music is a natural selling point and combined with lower backpressure for better power and economy, should make the DynoMax dual system an easy up sell from the boredom of stock pipes. Two is definitely better than one.

Watch Jim install the DynoMax system at

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