The bad news came with a loud clank, then a scrape. The rusted-out muffler and tailpipe assembly finally broke free from my much-loved 2004 Toyota Tacoma. The whole exhaust unit hit the pavement and dragged until I pulled over and got it off the ground with a bent-up metal clothes hanger. My buddies Bill and Mikey Phelps, who run Phelps Wholesale Auto in Lansing, N.Y., told me they couldn’t weld together my exhaust any longer—it was toast. So, it was time to pony up for a replacement, maybe even. But how did I end up with a MagnaFlow exhaust?
The MagnaFlow Exhaust Decision
I soon realized that there are three real options to consider when shopping for a cat-back exhaust system—that is, the entire exhaust system from the catalytic converter back, including inlet or middle pipes, a muffler or two, maybe a resonator and the tailpipe assembly.
The choice between different cat-back systems comes down to the simple formula that governs most things automotive: Performance equals money. I could go cheap, like Meineke cheap, and save some cash but stay even or even lose some horsepower. Using original equipment manufacturer (OEM) parts from a Toyota dealer was an option, replacing what fell off my old truck the week before, or I could pick something high-end like a MagnaFlow, Flowmaster or another third-party performance exhaust system.
An aftermarket exhaust costs more but sounds great and—in some cases—can boost horsepower. MagnaFlow says its customers experience around a 10-percent horsepower boost. I liked the idea of more power, and Uncle Sam had given me back some tax money, so what the hell, I thought. Two years after the install, the MagnaFlow exhaust remains one of the best upgrades I’ve ever done to my truck.
Science & Some Good Aftermarket Exhaust Tips
B.S. clamp-on muffler tips and other “add-on” muffler parts don’t do anything for performance. If you want more power to the pedal, the entire cat-back system needs to be replaced. When we cut mine out, it was clear that the catalytic converter was shot, too.
Over the last couple of years, it took additives, cooling periods and other hijinks to get my truck to pass the rigorous New York smog inspections, and now we saw why. I added a direct-fit MagnaFlow California-certified universal cat and two O2 sensors to the buy list. More money, yes, but the truck would sail through emissions inspections now, and it would be kinder to the environment.
Pipes & Gases
As for more horsepower, the science is simple. Wider pipes mean a more efficient path for exhaust gases to exit the engine. Air leaves the combustion chamber in the engine faster, so more fuel and air can be burned, creating more power and torque for a more efficient engine.
At low RPMs, the amount of gas leaving an engine is minimal, so wider pipes don’t create any low-end torque. An exhaust system could be restricted, the plumbing all made narrower with smaller pipes, which would increase the velocity of the gas being released on the low end, but it would kill high-end performance where more exhaust gas is generated. This buildup of back pressure in stock or smaller-sized exhaust systems makes it hard for gases to exit the engine when running hot, which detracts from the mid- to high-end power.
Larger pipes eliminate back pressure in this window and continue to do so higher into the RPM red zone than stock pipes. The gases are moving more freely, which means a boost in top-end power. This is what we’re talking about when we speak of exhaust systems and horsepower or torque: more efficient high-RPM combustion. It also means better miles per gallon, as the engine is working less to expel exhaust gases. (When I installed the MagnaFlow, I shortly thereafter put larger tires and a new suspension on the truck, so I can’t say whether my gas mileage improved. My guess is that it would have, but not by much.)
Catalytic converters aside, you’re really buying two things when you buy a high-end exhaust system: pipes and a muffler or mufflers. Generic factory and OEM pipes are “crush-bent” into shape. This makes a kinked or crinkled area around the bend, which decreases the pipe diameter and slows down escaping exhaust gas. Higher-end pipes are “mandrel bent,” which means the inside diameter is consistent and there’s less air resistance.
Mufflers generally work in one of two ways: They’re either chambered or straight-through. Chambered mufflers, like the Flowmaster, work by stopping and redirecting gases over baffles, sort of like a firearm suppressor. The upside is that most gearheads think chambered mufflers sound the best—a low and graveled prrrrrr like a big, mechanical cat. The downside is that the design restricts escaping exhaust and doesn’t produce the same performance gains as straight-through mufflers.
Straight-through mufflers, like the MagnaFlow, have a stainless steel, perforated core, stainless steel wool and sound-absorbent packing material that breaks in over time—it might take 400 or 500 miles for the pitch and tone to even out. There are no baffles, chambers, louvers or any restrictions at all in the straight-through designs. This means more wide-open performance and a deeper sound. The downside, for some, is that they tend to be louder.
The Aftermarket Exhaust Install
The hardest part of installing a new back-cat exhaust system on an old truck is cutting out the rotten and rusted stock pipes, especially if you live in a salt state like New York, where the undersides of everyone’s vehicles eventually turn to garbage. With some ramps and a torch, a shade-tree mechanic can do the work himself without much challenge. However, I called in my friends Mikey and Bill.
Mikey pulled the O2 sensors. Then he cut the rusted pipe into sections behind and in front of the muffler and the cat with a torch. They fell to the ground. He removed the back hanger and my front clothes-hanger job. Then he broke the nuts that held the inlet pipe to the manifold. The old exhaust was out.
Mikey installed the new system from the front of the truck on back while I snapped photos. He sealed all the joints with high-temperature red gasket maker. Everything hung loosely together until the last tailpipe assembly locked into place. Then he locked it all down with 40 inch-pounds of torque. In other words, he did it right. The whole process took less than half an hour.
My MagnaFlow Exhaust
When I turned the key, the first thing I noticed was the sound: A loud growl. The truck sounded custom—it sounded mean. Pulling out of the shop, I didn’t notice much gain in the pedal. Then I got on the highway and stepped on it to pass a semi. The increase was noticeable—10 percent? Maybe. I know it felt good, and it still does to this day.
Two years later, one of the main benefits to this MagnaFlow exhaust system that I didn’t really appreciate early on is the material. Every bit of it, from the muffler to the hangers and bolts, is stainless steel. So while the underside of my truck looks like a rust box, two winters later, the exhaust system looks clean. It’s solid as the day it went in. I’ve also passed two inspections with flying colors. All that and more top-end power—what’s not to love?
Gearheads will tell you that there are other, cheaper ways to boost a truck’s performance, and they’re right. But cats, mufflers and pipes rot and fail. Why not put one in that provides some gains, and—in my case—will last the life of the truck? It seemed like a no-brainer to me. Now, if only my engine would fail in a way that required headers or a supercharger. Then, as with this exhaust, I could throw up my hands and tell my wife, “I’ve got to get it fixed, honey!”
Why and How to Install the Aftermarket Exhaust – Ballistic Magazine is written by Michael R. Shea for www.ballisticmag.com