Flowmaster pioneered the art of exhaust acoustics. We've all experienced that Flowmaster phenomenon at one time or another, hearing the throaty "warble" of virtually any V-8 through dual mufflers and instantly recognizing them as Flowmasters. The "Flowmaster sound" is the epitome of American muscle car power.
Flowmaster's legacy goes back to 1983, when Sprint Car racers in California were faced with tough noise legislation. Flowmaster founder Ray Flugger developed a muffler that would quiet racing engines without compromising performance. At first, Ray's exhaust silencers were downright ugly. He even welded handles to them to make them easier to carry during testing. They became known as "suitcase mufflers," but their design was ultimately patented, the result of years of testing in very modest beginnings.
Those first Flowmaster mufflers came from a small barn in Northern California. Today, the company produces mufflers and exhaust systems from its state-of-the-art manufacturing facilities. In fact, Flowmaster operates the only research and design facility of its kind, using a SuperFlow SF-7100 engine dynamometer for testing. Ray Flugger remains active in the company, keeping a close eye on the legacy he created nearly three decades ago.
Flowmaster offers several choices for the Mustang's 45 years of production. That means there's a Flowmaster muffler designed specifically for your Mustang. Which type should you choose and why?
First, you need to choose either an entire exhaust system or a pair of Flowmaster mufflers that will fit your Mustang's existing pipes. Flowmaster does entire exhaust systems for all Mustangs except the '74-'78 Mustang II. This means complete systems for '65-'73 classics, '79-'04 Fox-bodies, and '05-'09 cars.
There are two basic Flowmaster American Muscle exhaust systems available with 2 ¼- or 2 ½-inch pipes for classic Mustangs. Two important points: They will not fit convertibles, nor are they compatible for the '65-'66 GT valance panel with trumpet tips. They employ late-model-style exhaust hangers. If originality doesn't matter, they offer an improvement over original equipment because they isolate noise and vibration better. If you must have original pipes and hangers, go with one of Virginia Classic Mustang's factory original-style exhaust systems and fit it with a pair of Flowmaster mufflers. We're going to show you both ways.
This is the Flowmaster two-chamber...
This is the Flowmaster two-chamber Series 40 muffler for classic Mustangs. If you like a throaty roar, the original two-chamber Flowmaster muffler, available from Virginia Classic Mustang, is for you. Be advised, these guys are loud with a lot of interior resonance. But you just can't beat the demeanor of the Flowmaster. Available in 19- and 23-inch lengths with two different types of pipe offset, they're a good fit for '65-'04 Mustangs, including '74-'78 Mustang IIs. All you need is a good exhaust shop that can do custom pipe bending.
Here's the Flowmaster Series...
Here's the Flowmaster Series 50 muffler (23 inches long as shown) which will fit underneath your classic Mustang, but it gets tight. Count on trimming tail and exhaust pipes for a good fit. The three-chamber Series 50 is quieter with a deeper sound.
Here's the 19-inch versus...
Here's the 19-inch versus the 23-inch overall length difference. The 19-inch Flowmaster is a perfect fit for '65-'70 Mustangs. The 23-inch muffler is a tight fit but works great with '71-'73 Mustangs.
This is our Turbo dual exhaust...
This is our Turbo dual exhaust system from Virginia Classic Mustang. We have removed the old mufflers to install 19-inch Flowmaster Series 50 Delta Flows. For the Delta Flow muffler to fit properly, we had to cut 2 ½-inches off the exhaust pipes to get our tailpipes and mufflers properly positioned.
Because 2 ½-inches...
Because 2 ½-inches gets into the exhaust pipe bend, Sergio's Muffler in Palmdale, California, had to both cut and expand the pipe end to properly fit our Flowmasters.
Our old mufflers had welded-on...
Our old mufflers had welded-on hanger brackets. Flowmasters do not, which presented us with a challenge-how to hang the exhaust system. AutoZone has two types of muffler hangers available from Hang-It-All. We suggest using the PN 17146 hanger kit (you will need two of them). All you will need is the pipe bracket (shown at the top here on the Virginia Classic Mustang factory muffler hanger). Modify the pipe bracket as shown and attach it to the factory hanger. At the bottom is the Hang-It-All PN 17175 hanger, also available from AutoZone stores. You can use the pipe hanger from this kit as well.
Here's the factory hanger...
Here's the factory hanger with parts from the Hang-It-All kit (PN 17146). Spacers are available at Lowe's or Home Depot to achieve proper height. If your Mustang originally had factory dual exhausts, you won't need spacers, just the modified pipe hanger bolted to the insulator.
This is the basic Flowmaster...
This is the basic Flowmaster American Muscle series exhaust system for '65-'70 Mustangs. For '65-'66, you get a stainless steel tailpipe tip and a choice of either 2 ¼- or 2 ½-inch pipes. For '67-'70, you get a 2 ½-inch pipe system with either GT valance (great-looking stainless tips) or non-GT valance (with turndowns).
Here's the hardware that Flowmaster...
Here's the hardware that Flowmaster provides with the American Muscle exhaust system. The hangers are late-model style, which isolates noise and harmonics better. However, they are not like original equipment. You can use this hardware kit or the factory original-style exhaust hanger kit from Virginia Classic Mustang.