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Maganflow Exhaust System Install - Boosting Efficiency

Posted in How To on July 1, 2009
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We have to admit that it's become pretty difficult to make much power these days with an exhaust system on a new model truck. The OEMs have gotten more proficient with their exhausts, and the power gains that you were able to achieve on 1990s-and-older trucks can be almost sliced in half on new trucks. This isn't to say that you can't still make power with an exhaust system on a new truck, but the cash you're spending will likely be more justified with a quality exhaust note rather than a seat-of-the-pants feel.

But on older trucks, say vehicles designed in the mid 1990s or earlier, you can still make some power by swapping on a high-quality exhaust system. In fact, we wanted to prove just that. We went to the only team out right now that can sell you a complete exhaust system from the exhaust manifolds to the tailpipe.

At the time of this article's inception, Car Sound, which you might better know by its muffler line, Magnaflow, is the only legal supplier of CA legal catalytic converters sold after January 1, 2009. You can still go directly back to the OEM, but get ready to pay more money for a piece not specifically designed for performance.

Besides being the only supplier of cat-included systems, Magnaflow has OEM-replacement systems that offer a nice, subtle rumble that we've really grown to like. They don't give the deafening tone that wakes up the neighbors two blocks away when you start up at night. It's usually around the ages of 22-25 that you start losing the yearning to be heard a mile away, and the entire staff of this magazine is more than a few years past that.

Something to note is that most Magnaflow exhaust systems are done to mimic factory systems -- they follow factory routing and don't go "overkill" with tubing diameter. A common misconception with exhaust is that you will increase efficiency (freeing up power) by moving to a larger exhaust tubing diameter. Well, there are a few common misunderstandings about this:

Let's deal directly with the "bigger is better" fallacy first. OEM exhaust suppliers usually make exhaust systems out of tubing that is optimal for the power a stock engine puts out. If you start increasing the power with aftermarket mods (we're talking more than 20hp worth), then you can perhaps free-up some potential power by moving to a larger tubing diameter.

The next thing we want you to understand is that exhaust is only as free-flowing as its most restrictive point. That's where many aftermarket exhausts make power -- by smoothing out abrupt turns in pipes and mufflers. This is also something you should remember about increasing exhaust tubing diameters: if you are going to a larger tubing size behind the cats but still have tiny tubes from the headers, then you really haven't freed up much power with the larger pipes.

Lastly, we'd like you to know that you can actually lose power by going to too large of a tubing diameter with your exhaust. You commonly hear backpressure touted as a "bad thing," and bigger pipes are a good way to lessen it. But you need some backpressure for a properly working exhaust system. Too much and it will stifle your exhaust, but too little and you'll be throwing power away.

We tried adding a complete Magnaflow exhaust -- catalytic converters and cat-back exhaust system -- to our 1990s -era ride to see what kind of power we could make. Magnaflow had a Dynojet dynamometer on-site, so we could easily get results of just how much a new exhaust helped our workhorse Durango.

How About the Results?
We were really happy with the new exhaust system. It wasn't just some spliced-in muffler-- it was a complete new system that purred of subtle performance. We were a little worried about swapping an aftermarket muffler onto our daily driver, as silence can be golden when you spend too much time in trucks, but the stainless Magnaflow system gave a smoother but not much louder tone that was pleasant.

The dyno showed a peak improvement of almost 19hp and 20 lb-ft of torque. Driving around, we felt a little more kick off the line and were able to use a little less pedal when cruising around, so there was a noticeable difference.

We actually noticed fuel economy increase slightly as well (about 20 more miles per tank). Besides being "greener" by using less fuel to go the same distance, we are sleeping better at night knowing that one of our older rides is running cleaner than required with the most current and effective catalytic converters available right now.

Dyno Results
STOCK EXHAUST DYNO RUN: 175.20hp, 312 lb-ft torque
MODIFIED EXHAUST DYNO RUN 1: 193.83hp, 332.54 lb-ft torque
MODIFIED EXHAUST DYNO RUN 2: 191.41hp, 328.22 lb-ft torque
PhotosView Slideshow


Magnaflow/ Car Sound

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