My ’99 GMC Sierra is in serious need of some new exhaust. The old system looks like Swiss cheese and the cab fills with smoke at red lights. It really makes for one-hell-of-a headache. Plus, the rumble is loud enough to crack plaster, which makes me the scourge of my neighborhood. I figure it’s time to outfit that old rig with some new exhaust tubes.

The old war bird has done me right over the years. Kept the construction money flowing in the boom times; got me to the unemployment office in the flat times. She never fails to start and I can load ‘er down like no one’s business. It’s only fitting that I outfit her with a real nice exhaust system.

I read the truck mags and forums and I’m down to 2 brands—Magnaflow and Flowmaster. Both are popular with the truck crowd, each camp claiming their brand is king. Instead of listening to a bunch city-slicker fools, I got to the bottom of this myself. Let’s start with Magnaflow.

Magnaflow has been in the performance-exhaust game for about 25 years. They’re located in southern California—the heart of hot-rod country. Magnaflow banners are plastered all over the race tracks and a fair amount of the racers are using ‘em.

Like all the other exhaust makers, Magnaflow yammers on about mandrel-bent this and that. Since that means nothing to me, I need some numbers. The Magnaflow kit for my rig claims 22 horsepower and 22 ft-lbs of torque. Not bad considering me and my buddy Bobby can bolt it up in a coupla hours. For the price, it works out to about $25 per horsepower gained.

What about Flowmaster? Again, it seems like all exhaust companies want us to believe mandrel-bending is akin to the second coming. I mean, does anyone crush-bend their tubes? Come on guys, tell us something new.

Anyway, back to Flowmaster. These guys have also been around for about 25 years. They hail from northern California—the heart of hippie country. But, I won’t hold that against them. Flowmaster systems are really popular with racers and they seem to dominate the other companies in brand visibility.

The Flowmaster system for my rig claims—you guessed it—22 horsepower. Of course, the Flows cost a little less, averaging about $20 per gained horsepower. The difference is the material. Flowmaster uses aluminized steel, Magnaflow uses stainless. This could come down to a longevity issue.

Since I really love my old Betty, she’s getting’ the Magnaflow system. I plan to keep ‘er for the duration, so stainless steel is the way to go. As far as performance, both brands seem to deliver about the same power and torque.

There are a lot of performance exhaust companies out there. Of the two tested, Magnaflow runs about a hundred bucks more, but you get a stainless steel system. Flowmaster has greater brand recognition and are made of aluminized steel. Bottom line is both companies make a flawless system and you end up the winner.