Mark Houlahan
Tech Editor, Mustang Monthly
November 3, 2009

Horse Sense: As with most X-pipe designs, MagnaFlow's is said to offer performance improvements without an obnoxious exhaust note to turn you deaf. As you will see by the Dyno Doings sidebar, we did make some nice power numbers, but our exhaust was none the quieter-although it wasn't any louder either. We can only suspect the Steeda side-exit after-cat system, which exits right at the side windows, keeps the exhaust note close to what it was before (with the stock H-pipe) due to its exit location. The sound is truly sweet when it bounces off traffic or close buildings, so we're not complaining.

Our 3g GT's exhaust modifications to this point have been limited to the Steeda side-exit exhaust kit. While the kit looks awesome and has a great sound to match, our P-1SC-blown '01 needs more. If there's one thing blower cars like, it's bigger exhaust. There's no need to throw big bucks on the intake side of things right away, as the blower is forcing the air into the engine, artificially increasing the volumetric efficiency of the engine, if you will. Of course, intake-side modifications will still reap some horsepower benefits, but the exhaust side of the equation is where your money will be better spent (in street applications at least).

To that end, we wanted to help our 3g GT exhale a little more easily, while retaining the converters (we have to live on this big rock, too, you know). Since we hope to install a 5.0 stroker mod motor at some point, we opted to avoid the headache of installing headers on our Two-Valve at this time. That left us with but one area to wrench on-the stock four-cat H-pipe that sat between the stock headers and our previously installed Steeda side-exit system.

We placed a call to MagnaFlow for its Tru-X crossover pipe with con-verters (PN 93335). We've installed MagnaFlow's after-cat systems before with great results. And though its newest Tru-X is for Fox 5.0s (see "Ignite the Future," Mar. '02, p. 171), our past experience with the part's fit and design is what had us picking up the phone and calling MagnaFlow.

Dyno Doings
Of course, we usually can't install a part without dyno testing it. So, to make everything right in the world, not only did we have the great folks at Lugo Performance install our new MagnaFlow Tru-X high-flow-cat crossover pipe, but we also had them twist the dyno rollers. Dyno king Eddie Burke was all too happy to get behind the wheel of his favorite yellow project car and beat it to within an inch of its warranty to see what our new Tru-X system was worth.

Though we lost a bit of baseline power from our previous pulls-likely due to increased heat and humidity since our last test-we found a gain of 34.8 hp and 21.4 lb-ft of torque from the addition of the X-pipe. These are solid numbers that are no doubt helped by the fact that our 3g GT's ATI P1-SC blower (or any blower for that matter) really likes a free-flowing exhaust.

After wrapping up our back-to-back testing on the Mustang MD-1750 dyno, we had Eddie run an "unloaded" test to see what kind of numbers we should expect on a dyno, such as a Dynojet. Eddie says experience with customer cars shows the unloaded MD runs are within a couple horsepower of the same car run on a Dynojet.

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More interesting test data came from a freshly installed multi-input temperature sensor system. At the Reynolds, Georgia, NMRA race, we made a couple of co-pilot passes with ATI's Dan Jones driving the 3g GT. We weren't focusing on the e.t., but rather documenting the air temperatures seen in the car's inlet tract. The sensor was set to measure ambient air at the air filter, air leaving the supercharger, and air leaving the intercooler. At the track, the intercooler dropped the inlet temp by a peak of 140 degrees, which was certainly impressive. At the top end, we checked the ambient temp, and it was about 97 degrees. Then we made a second pass looking only at the temp coming out of the intercooler, and the temps peaked out at 116 degrees, while the ambient temperature was 99 degrees. So the boost entering the engine was only 17 degrees above ambient.

How does 100-mph air over the intercooler compare to a mere fan on the stationary chassis dyno? Well, we made two X-pipe pulls to ensure the car was repeating. On the first pull, ambient air was 97 degrees, and the air entering the engine was 137 degrees. The second pull produced nearly identical numbers. So, the air was 40 degrees above ambient on the dyno. Granted, the track and dyno runs were in different climates, but it goes to show the air-to-air intercooler cars may need different tuning for dyno and street/track to fully capitalize on the intercooler's dividends.

BaselineMagnaFlow Tru-XUnloaded (w/ Tru-X)
2,600237.70118.89106.75 56.24114.22 60.49
5,500 n/a n/a311.67326.74345.69362.71
5,600 n/a n/a309.86328.80342.03365.13
5,700 n/a n/a308.05330.87338.38367.55
5,800 n/a n/a299.07330.25335.67370.90
5,900 n/a n/a122.86132.76328.79369.65

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