Hennessey Exhaust System on a 2nd Gen Probe GT
Note - Hennessey Motorsports no longer supports any parts for the Probes, due to lack of intrest. But if you plan on upgrading your Viper, check out their Web page at - http://www.hennesseymotorsports.com/
From Motor Trend, December 1994
Add a few horsepower to the 2-ton Impala SS and only your imagination will feel it. But on something feathery, the addition can make a dramatic difference. At about 2,700 pounds, Ford's Probe GT lies toward the lightweight end of the performance-car spectrum, so the simple, relatively inexpensive modifications offered for it by Hennessey Motorsports pay off impressively. Hennessey's PowerDesign air filter and stainless steel exhaust don't transform the refined Probe into some berserk NASA rocket sled, but they do add a performance edge to a car that may be too civilized for enthusiasts.
At only $150, the PowerDesign air filter is an open design with a washable and reusable element. Hennessey claims 8 horsepower for the PowerDesign, and considering its simplicity, that's reasonable. In the tightly packed, highly styled Probe engine bay, the big filter dwarfs the 2.5-liter 24-valve V-6 and doesn't look well integrated with the other components. However, the workmanship is impeccable.
More effective, more exciting, and flat gorgeous, Hennessey's stainless exhaust makes a big difference on the Probe. The Hennessey system takes the Probe's normally suppressed idle and deepens it into a lionlike purr. It transforms the car's character; the stock Probe's subdued competence becomes an eager, predatory arrogance. Running up through the gears produces a high-rev contralto, while each downshift elicits an athletic rasp. Hennessey contends its exhaust produces 16 extra horsepower, but just the sight of the 3.5-inch-diameter polished tip poking out from under the rear bumper is nearly enough to justify its $350 price.
Add the intake's 8 horsepower to the exhaust's 16 and the result should be 24 more ponies propelling the Probe (up to 188). Except for replacing the stock units with a set of DP's new bargain-priced Impressions wheels and a new Centerforce clutch, the Hennessey exhaust and PowerDesign were the only changes to the 27,000 mile '93 Probe MT tested.
Most of the extra power Hennessey adds to the Probe exists at the upper end of the powerband. Just as the tach swings past 5,500 rpm, the car gets a portion of torque not present in the stock version. This shows up in the 0-40 clockings where the Hennessey car is 0.4 second quicker than the factory Ford. The Hennessey maintained its acceleration advantage throughout our test, knocking back a confident 7.3 second 0-60-mph clocking (0.2 better than stock) and winding up with a 15.5-second elapsed time through the quarter mile with an 89.5-mph terminal velocity (0.3 seconds and 2.3 mph better than stock).
The emissions paperwork is still pending, but for only $500, the Hennessey parts seem a good value for the Probe owners who want to reignite their automotive love affair and enjoy a good snarl.