There's no denying the fact that DaimlerChrysler's third-generation 5.7L thin-wall-casting Dodge Magnum Hemi (as found in the Dodge Ram 1500 and 2500 models and Heavy Duty Dodge Ram 3500 models) certainly has a reputation to live up to. It's the proverbial father: The 426 Stage III Gen. II Hemi, manufactured from 1964 to 1973, absolutely ruled the roost in the mid-'60s NASCAR Grand National stock-car competition, as well as in all classes of NHRA drag racing. Although DaimlerChrysler's sales literature factory-rates the new Hemi at 345 hp with 375 lb-ft of torque, independent dynamometer test figures are somewhat more conservative.
The folks at Kenne Bell Superchargers, Performance West, and Doug's Headers have recently conducted a series of pulls, which rated the stock 5.7L at a more conservative 263.4 hp at 5,500 rpm and 281.5 lb-ft of torque at 4,400 rpm. That's still pretty good for a small- or medium-block V-8 engine, but we all know that number can be pumped up.
How, you ask? With a set of equal-length four-tube headers and an after-cat, which is a direct replacement for the stock 5.7L Magnum Hemi exhaust system. Manufactured from mandrel-bent 1-5/8-inch-diameter mild steel tubing, the headers feature 1/2-inch-thick laser-cut header flanges, three-bolt collector flanges, a 3-inch stepped collector, a 2-1/2-inch crossover pipe with a forward O2-sensor provision, and a 2-inch slip-fit reducer cone.
Installation time is about two hours using common shop tools and jackstands (a hydraulic lift makes the going a lot easier). Each set of Doug's headers comes with all the necessary mounting hardware, fasteners, header gaskets, and fully detailed instructions.
How well do these headers perform? Back at Kenne Bell's dynamometer cell, the same truck was fit with a set and retested. Would you believe a reading of 299 hp at 5,400 rpm and 313.4 lb-ft of torque at 4,400 rpm? That's 35.6 more horsepower and almost 32 more lb-ft of torque just from bolting on a set of headers. But wait - there's more.
"Not only did we want to make the 5.7L perform like a traditional Hemi, but we also want to make it sound like one," said Doug Thorley of Doug's Headers. This feat was accomplished with the development of a bolt-on after-cat dual-exhaust system, consisting of a pair of 2-1/2-inch-diameter exit pipes running from a modified 6-inch after-cat pipe (with a rear O2-sensor provision) to either a pair of 14- or 18-inch straight-through muffler casings. The size of the casings is dependent on the amount of rumble you're looking for.
From the mufflers back, the remainder of the system consists of 2-1/2-inch-diameter pipe. Doug's new dual-exhaust setup also employs a pair of mirror-polish stainless-steel bolt-on exhaust tips to give the Hemi just the right look. Follow along as the old header master personally installs a complete Hemi Header and after-cat exhaust system beneath an '03 Dodge Magnum 2500.
1.The pipes from Doug's Headers...
1.The pipes from Doug's Headers have 1/2-inch-thick laser-cut header flanges and a 3-inch collector. You know they're nice pieces.
2.The perfect complement to...
2.The perfect complement to the headers is the company's after-cat dual-exhaust setup. Available in either black or thermal-barrier-coated silver, the system consists of a 3-inch-diameter, 6-inch-long after-cat pipe, with a rear O2-sensor provision and a pair of 14- or 18-inch flow-through muffler casings with 2-1/2-inch tailpipes.
3.The first order of business...
3.The first order of business was to place the truck on a lift and remove the wheels. The factory plastic inner fender panels, which are held on with eight 8mm bolts, were removed to provide access to the cast-iron exhaust manifolds.
4.After disconnecting the...
4.After disconnecting the forward O2 sensor from the factory Y-pipe, our technician removed the Y-pipe assembly using a 9/16-inch socket and extension.
5.The removal of the actual...
5.The removal of the actual exhaust manifolds came next. A 10mm socket was used to remove the factory header bolts, while a 12mm socket was required to remove the factory heatshields.
6.Prior to the actual header...
6.Prior to the actual header installation, a liberal coating of Permatex High-Temperature silicone coating was applied to the header flanges. The new header gaskets were then installed, using masking tape to keep them in place.