Steve Baur
Former Editor, Modified Mustangs & Fords
April 13, 2006

Since receiving the '05 Roush Stage 2 Mustang last summer, we've logged over 7,000 miles on it and have enjoyed every one of them. Normally, we have press cars for a week or two and that's it, so when we noticed the Roush had been hanging around for three weeks, and then two months, we knew something was off its axis.

Bottom line was, Roush wanted us to experience its car the way the typical owner would. Let's face it: You can only learn so much about a vehicle in seven days. Ultimately, we have to extend our compliments to Roush and its engineers. Except for the drone of its exhaust at certain rpm (and the exhaust tip that someone pilfered), our relationship with this car has been a delight. Unlike some temperamental tuner cars with bone-jarring rides, the Roush has exhibited no bad manners. The ride is as smooth as factory stock, yet the grip is akin to a race car. The body kit, wheels, and stripes get stares and compliments from bystanders wherever we take it.

While we have appreciated the extended seat time in the Stage 2, our main gripe has been the stock 300hp 4.6 under the hood. When you drive something that screams, "Race Me!" (at 40,000 clams, no less), you'd better have more oats in the feedback than Dearborn supplies. The horse-power junkie in all of us wanted to strap on a supercharged Roush Stage 3 Mustang and see what it has to offer.

Then, the powers that be at Roush decided to have us upgrade the Stage 2 to its big brother's specifications. That's right, we're going to mod a press car and get away with it.

Here's what makes the Stage 3 Roush a thoroughbred. The supercharger system retails for $5,699 and includes everything you think the factory would have included if it was selling it over-the-counter. It's that inclusive.

While we'll be foregoing the small blower pulleys and custom ECM tunes, what we will have once we're finished is an emissions-legal, fully warranted package that should improve on the Stage 2's already stellar foundation. Later installments will see the Stallion fitted with Roush's Stage 3 brakes, its lighter (by 11 pounds each) forged aluminum wheels and shifter.

In this installment of the Mustang's transformation, we installed the RoushCharger, which is an M90-size, Roots-style supercharger that pumped up this Mustang's power output from a stock 251 rwhp to 370 rwhp. Torque also improved from 275 lb-ft to 350. It should be noted that the RoushCharger is available over-the-counter to anyone with an '05-up Mustang. Best of all, it will not, according to Roush, void your precious factory warranty.

One thing we noticed prior to our baseline runs was that the passenger-side rear brake caliper seemed to be hanging up for some. The rotor was actually puffing a bit of smoke after each dyno pull, so we may have lost a few horsepower there, but the issue was resolved prior to thrashing the Roush with the supercharger.

The addition of the RoushCharger and its new ECM tune generated 370 hp and 350 lb-ft of torque to the rear wheels. Air/fuel ratio checked in at about 12.9:1. This is with 5 psi of boost, which is the only way the kit comes.

At $5,699, the RoushCharger is not the most inexpensive supercharger on the market, but as Crazy Horse Racing's owner Chris Winter put it, "This is the most well-engineered supercharger kit we've ever seen."

Which should not be unexpected at this price, especially considering Roush does a ton of OE-engineering for Ford and numerous other car companies.

What was unexpected was what appeared to be a severely rich issue we encountered after the dyno pulls on our way home. Everything was fine until we were about 20 miles from the shop, when the car began stumbling and losing power.

After contacting Roush, we were informed of a spark plug fouling issue that they believed they had solved with the latest ECM tune they had sent us. A new set of spark plugs did not resolve the issue, which left us scratching our heads. Until, that is, the folks at Roush asked if we had torqued the spark plugs, per the directions. We sheepishly admitted we hadn't. In went yet another new set of plugs and this time we properly torqued them down. Strange as this sounds, it completely cured the problem. The ride home was uneventful, except for us enjoying the monster's extra 120 hp.

In our next installment, we plan to install and test the Roush Stage 3 front brake package. This will cure the car's biggest deficiency on the road course, which was the stock binders. Then we'll have to say "Adios" to the Stage 2 Stang. They're gonna have to pry the keys from our hands.

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