Sometimes it may not seem like it, but we've heard you when it comes to the Mustangs you're really driving, modifying, and wanting to know more about. And you're right, they are not (mainly) the sexy new '05s or in many cases even the pushrod 5.0s, but rather the familiar '99-'04 GTs.
Why those years? Because they are good years. Nothing against the pushrod 5.0s, we named a magazine after them you may have noticed, but those cars are on the backside of the curve, old enough to need restoration, and two generations short of today's quality and refinement standards when it comes to first line, daily driving cars. And we dig the new '05 Mustangs, but there just aren't that many of them yet. The '96-'98 GTs, with their anemic version of the 4.6 Two-Valve engine, are out there, but they're not your main squeeze, either. Not that they're bad cars, but they do require the better performance improved cylinder heads that came stock on the later '99 and '04 machines. Which means if you're playing with an affordable, widely available Mustang, you're likely playing with a '99-'04. Good for you.
Now, how do you modify these cars to best effect? That's what we set out to illustrate in this story. To get the latest poop we burned up the phone lines talking to tuners and parts retailers to get their input on what people are doing and should be doing to the New Edge cars. And just so you know, our main contacts were Brothers' Performance Warehouse, Fairway Sport & Performance, GTR High Performance, Maximum Motorsports, Paul's High Performance, plus a host of specialty shops and parts manufacturers.
What People Are BuyingOur first question to the parts houses was what are people actually buying for '99-'04 GTs? The short answer is, "all the usual bolt-ons," but of course, there's more to it than that.
For starters, these cars are almost totally street cars. Track duty seems a strong point of the lighter, less expensive 5.0s, and the '99s are still young enough to be presentable in daily driver duty. So, people are modifying their cars to drive better on the street, with a small percentage of folks spending the cash for some track action.
The big dividing line is supercharging. If you have the $3,500 or more for the blower, great-it's one of the best bangs for the buck. If not, then "the usual bolt-ons" make the most sense.
So, from a plain, old dollars viewpoint, it makes sense that bolt-ons predominate. Easily the most popular of these are intake improvers-cold-air kits and throttle bodies-along with freer-flowing exhaust bits-X-pipes and after-cat muffler systems. Lately, intake air plenums have risen to major league 4.6 bolt-on status.
Because many people run cat-less off-road X-pipes, and these cars use four oxygen sensors, the check engine light burns eternally in many '99-'04 cars. To get around this, MIL eliminators are big sellers because they turn off the check engine light. For the same reason, some sort of electronic tuning aid also sells. The Diablo-Sport Predator seems to lead this list.
As always, steeper rear axle gears are super popular. The typical all-around gear set is the 3.73, with the 4.10 for the more aggressive customers. Because these cars use electronic speedometers, some sort of speedometer recalibration tool is needed after a gear change, so those also are easy sells.
Off-road pulleys are just as popular as ever on the '99 and up machines. They're relatively affordable, easy enough to install, and even simple enough to remove if you want to go back to stock or keep them when selling the car.