Dale Amy
January 15, 2010

Horse Sense:
DynoMax uses a patented process called Forstadt Inside/Outside Bend to manufacture the internal perforated tube on Ultra Flo mufflers. This process prevents tube distortion and results in maximum exhaust flow and performance. In addition, the FIOB process increases the tube area for improved sound absorption. Ultra Flo cans are characterized by deep tones and reasonable decibel levels

DynoMax is a familiar name in Mustang exhaust systems, so it should come as no surprise to see the company weld up versions for the '05 Mustang GT. Two versions, to be precise: the cost-effective aluminized mufflers we're installing here, as well as a polished T304 stainless offering for those seeking the ultimate in longevity and flash, and willing to pay for it. Both are based on DynoMax's well known fully-welded Ultra Flo architecture, which has a patented continuous straight-through perforated flow-path tube surrounded by continuous roving fiberglass. Ultra Flo cans are characterized by deep tones and reasonable decibel levels.

We were doing some other tech at Paul's High Performance when the DynoMax crew swung by with this prototype set of aluminized '05 Ultra Flo mufflers and an otherwise stock, new automatic GT (actually one of its staff company cars) to try them on. Installation's a snap, and our dyno sidebar tells the power story.

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The Sound of Power

  Baseline DynoMax Ultra Flo Difference
RPM POWER TORQUE POWER TORQUE POWER TORQUE
2,700 122.9 239.1 124.6 242.3 1.7 3.2
2,800 125.1 234.7 127.2 238.5 2.1 3.8
2,900 128.7 233.2 130.9 237.1 2.2 3.9
3,000 133.6 233.9 136.0 238.1 2.4 4.2
3,100 139.6 236.4 142.1 240.7 2.5 4.3
3,200 146.6 240.7 149.1 244.8 2.5 4.1
3,300 153.9 245.0 156.5 249.1 2.6 4.1
3,400 160.5 247.9 163.3 252.2 2.8 4.3
3,500 165.6 248.5 168.8 253.2 3.2 4.7
3,600 169.4 247.2 173.4 253.0 4.0 5.8
3,700 173.2 245.8 178.1 252.8 4.9 7.0
3,800 178.0 246.0 183.6 253.7 5.6 7.7
3,900 184.1 247.9 190.1 255.9 6.0 8.0
4,000 190.7 250.3 196.9 258.5 6.2 8.2
4,100 196.9 252.2 203.0 260.1 6.1 7.9
4,200 202.2 252.8 208.0 260.1 5.8 7.3
4,300 206.6 252.4 211.9 258.9 5.3 6.5

4,400 210.5 251.3 215.7 257.4 5.2 6.1
4,500 214.5 250.4 219.8 256.5 5.3 6.1
4,600 218.8 249.8 224.1 255.9 5.3 6.1
4,700 222.9 249.1 228.1 254.8 5.2 5.7
4,800 226.6 248.0 231.5 253.4 4.9 5.4
4,900 230.1 246.7 234.7 251.6 4.6 4.9
5,000 233.1 244.8 237.4 249.4 4.3 4.6
5,100 235.1 242.1 239.3 246.5 4.2 4.4
5,200 236.4 238.7 240.3 242.7 3.9 4.0
5,300 237.0 234.9 239.8 237.7 2.8 2.8
5,400 237.7 231.2 239.3 232.8 1.6 1.6
5,500 239.4 228.6 240.5 229.7 1.1 1.1
5,600 241.1 226.2 242.1 227.1 1.0 0.9
5,700 242.1 223.0 243.0 223.9 0.9 0.9
5,800 243.0 220.1 243.9 220.8 0.9 0.7
5,900 243.6 216.8 244.4 217.5 0.8 0.7
6,000 244.7 214.2 245.6 215.0 0.9 0.8
6,100 244.1 210.2 245.4 211.3 1.3 1.1
6,200 240.9 204.1 244.1 206.8 3.2 2.7

A great way to sample a muffler's singing voice is to stand somewhere downstream as a dyno pull is made. So we did. How would we describe the sound? Well, if you've heard DynoMax Ultra Flo mufflers before, the tones should be familiar, as internal construction is unchanged on these '05 versions. Far from raucous, the overall impression was of a subtle but deeper tone, such as going from a 10-inch subwoofer to a 12-inch. That speaker analogy is applicable to mufflers since both are extremely subjective-one man's sonic perfection may be another's nightmare. The bottom line is there's unlikely to be a huge power differential between the various aftermarket exhaust manufacturers, especially if only swapping mufflers, so if you hear a setup you like, go for it. DynoMax has some recorded sound bites of their systems on their Web site, but nothing specific (at least as we write this) to the '05 GT.

As for power, the DynoMax muffler swap generated a notable 6.2 hp and 8.2 lb-ft gain at a usable 4,000 rpm. Oddly enough, the gains diminished near the top of the tach arc. Whether this had something to do with variable cam timing, electronic throttle control, or some other factor is unknown-no attempt was made to recalibrate for the freer flowing mufflers, and we're still learning the various idiosyncrasies of the Three-Valve and its Spanish Oak brain. Regardless, the Ultra Flo mufflers did have a positive effect on power throughout the entire rpm band and, truth be told, most people buy exhaust components for auditory reasons anyway. Any additional power gained from the new parts is icing on the cake.

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