Check an innocuous box marked "WU8" on the order sheet to get the SS option, and the bottom line jumps by $3500-and all sorts of wonderful things happen. You get a bulging composite hood with a functional scoop that works with intake breathing efficiency mods and a reduced back pressure exhaust system to provide a 15-horsepower, 10-pound-feet peak output bonus. That pushes the new dyno crest to a total of 320 horsepower at the same 5200 rpm, and torque rises to 345 pound-feet at 4400 rpm (from 4000 rpm in Z28 trim). Out back, a 3.5-inch stainless exhaust tip improves appearance and flow. On the chassis side, the SS rides on 17-inch wheels that wear big P275/40ZR17 Goodyear Eagle F1s-a significant step up from the P245/50ZR16 Goodyear GS-Cs that are the top offering on the Z28. Spring and damping rates have been increased, and the front anti-roll bar has been fattened, too. The SS has its own unique spoiler with an LED high-mounted stoplamp, along with SS badging to distinguish the car from the "mere" Z28. In all, that's a lot of good stuff for just $3500. It's no wonder Chevy's working at its capacity of 140 SS units a week just to meet demand.
Like the SS, the Roush Performance Stage III Mustang offers a similar through-the-dealer buying experience, complete with full warranty and even financing if you so desire. Typically sold on an order-basis, the Roush Performance Mustang benefits from the vast engineering resources of Jack Roush's empire. Though you may only be familiar with the firm's long, colorful racing history (spanning 25 years and almost 200 wins in NASCAR Winston Cup, Busch Grand National, SCCA Trans-Am, and IMSA GTO), the core of Roush's business is actually powertrain development and vehicle prototyping for Ford, Chrysler, and General Motors. The majors come to Roush with hat in hand for its state-of-the-art capabilities, 35 different facilities, and 700-plus engineers.
Created in 1995, Roush Performance aims to channel some of that talent directly to the man on the street via a network of 200 Roush Ford dealers. So far, about 500 Roush Mustangs (in various levels of tune) and 100 Roush F-150s are on the loose in America. The latest of the breed, the Stage III Mustang we tortured, can be bought brand new, fresh from one of Roush's regional conversion centers, or can be carried out as a $17,400 conversion to your existing '98 Mustang GT. There are faster cars in the Roush Performance arsenal (like the Stage II supercharged Cobra that makes almost 400 horsepower), but the torquey Stage III car based on the Mustang GT is considered the best overall package of power, handling, and braking enhancements.
From the Mustang GT starting point, Roush engineers set out to crank up the intensity on every aspect of the car's performance, and push it well beyond the stock twin-cam Mustang Cobra in the hierarchy of high velocity. Given the basic GT's modest output-215 horsepower and 285 pound-feet of torque-step one was to scare up a bunch more power. This was accomplished using an extensive variety of parts developed jointly by Roush and Ford SVO (Special Vehicle Operations). Most notable is a Roots-type supercharger that develops a peak boost of 6 psi. Packaged tightly in the engine's vee and driven by a serpentine accessory belt, the Roush blower has the look of a completely factory installation. It crams mixture into a pair of SVO high-flow aluminum cylinder heads that sport enlarged and repositioned valves and specially shaped ports.
The exhaust beats a hasty exit through SVO stainless-steel shorty headers and a waaaay-sexy Roush side-exit exhaust system. Other Roush bits are sprinkled elsewhere throughout the powertrain, including a low-restriction air filter, new engine-management computer, and a short 3.55:1 rear axle ratio. For no extra charge, you can choose an even stouter 3.73:1 ratio.
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