Stock '99-'04 GT exhaust manifolds...
Stock '99-'04 GT exhaust manifolds are cast iron, which isn't the lastword in weight reduction. But, they are free, essentially leak-free, anddurable. They also fit the tight engine compartment well.
Underdrive pulleys are next. Again, the market has stabilized on saneunderdrive percentages, so there is little chance you'll fall prey tothe "race-only" mentality when it comes to pulleys. The alternatorstill needs to produce juice at low rpm, and the water pump still needsto turn at stoplights, and after years of over-slowing 5.0 engineaccessories, the industry has found a good balance with the street 4.6market.
One option the 4.6 pulley buyer will face is the type of pulley to useon the harmonic balancer. Because the 4.6 engine integrates the crankpulley with the harmonic damper into a single piece, you either replacethe entire balancer/pulley unit, or fit a piggy-back pulley over theexisting pulley. Our tuners recommended the one-piece damper/pulleyreplacement method as the installation is the same (you have to pull theharmonic damper in either case), and the replacement style keeps theharmonic balancer in the stock location on the crank snout. The slip-onpulley moves the balancer forward on the crank, which doesn't seembeneficial to the crankshaft, and can foul the transmission oil-coolerlines on automatic GTs. Popular brands in the pulley arena are ASP andSteeda, as well as pulley perennial March.
Headers for '99-'04 GTs make...
Headers for '99-'04 GTs make a handful of horsepower because there isn'tmuch room to get creative in their design. They make more sense onceyou've exhausted other bolt-on possibilities.
Another major pulley consideration is if you plan on supercharging your4.6 at a later date. All supercharger kits--roots, screw, andcentrifugal--are designed to work with stock crankshaft and accessorypulleys. So, if you buy underdrive pulleys now, then a supercharger ayear from now, you'll find yourself needing to reinstall your stockpulleys. And you did keep your stock parts, didn't you?
Advice from the vendors and tuners was to simply stick with stockpulleys if you plan to supercharge at some date. Inevitably, it savestime and money.
While on the subject of supercharging, there doesn't seem to be theblower envy among 4.6 owners as there is among 5.0 and Mustang Cobraowners. For a fun daily driver, you can have a good time without asupercharger--on the other hand, a blower makes great street power anddefinitely has sex appeal. It's also a fair chunk of change, and in theend, a question each owner must decide on for himself.
Where the blower question is appropriate for bolt-on buyers is onceagain, will there ever be a blower on this car? If yes, then what kindof supercharger? It's important because there is little sense indressing the engine with a bunch of bolt-ons that either must be removedor are supplied with the blower kit. That, and optimizing thesupercharger combination calls for slightly different components than anaturally aspirated one will.
Don't Forget Maintenance
Premium shocks are fast movers...
Premium shocks are fast movers on late-model GTs--both Konis andBilsteins seem the most popular. Your best buy is to get springs andshocks in a package.
Although still fairly new, many of the GTs we're talking about havereached the age where major maintenance items are due for renewal. Thisincludes things such as brake pads and clutches.
It's interesting that something like a stock clutch hangs in therepretty well behind bolt-on power modifications, but when it comes timeto replace it, aftermarket clutches are all anyone buys. Either peoplebelieve aftermarket parts are better than factory parts, or preparationfor more power production is taking place.
No matter, the point is, budget a little something for all thosewindshield wiper blades, filters, brake pads, clutch jobs, and so on.You don't want to max the credit card on exciting go-fast parts only tofind you need a set of tires, brakes, and a clutch all at the same time.
Ford Racing offers the red...
Ford Racing offers the red Bullitt brake calipers in its catalog. Theyhave become a popular upgrade because the price is reasonable, the redpaint and pony graphics dress-up the exterior, and they provide a bitmore clamping power. They can be combined with any number of largerbrake rotors, too.
As examples, a throttle body, plenum, and 4.10 gears are great on anaturally aspirated Mustang, but if you later fit a Kenne BellTwin-Screw blower, you'll find the kit comes with its own throttle body,eliminates the elbow, and makes so much torque that 3.73 gears arefaster than 4.10 cogs, and you might even be happier with 3.55s, orhappiest playing the cheapskate and staying with the free 3.27s. On theother hand, go with a centrifugal such as a Paxton or Vortech, and thebig throttle body and elbow will support extra power, and those 4.10gears will still pull the Mustang out of the hole until the blower boostbecomes meaningful around 3,750 rpm.
At this point, the average owner has reached the practical end to hisengine modifications. The fuel and ignition systems are quite good fromFord and don't need any help at the bolt-on (non-blower) level. Thatmeans the stock fuel pump and stock 80mm mass air meter ought to see youthrough the bolt-on stage. Of course, if you go past bolt-ons, you'llneed to step up the fuel system, and possibly the ignition system if youreally turn up the boost. But at 300 rwhp, the stock gear is OK.
Excellent braking is becoming...
Excellent braking is becoming a hallmark of late-model performance carsof all types. When more than just a good pad or simple caliper upgradeis desired, Baer Braking systems offer mild-to-wild brake improvementsthat achieve the superior feel and impressive fade resistance of trulyhigh- performance braking.
Attention should then turn to the chassis if it hasn't already. Wheelsand tires are a subject unto themselves, so we'll pass by them here,other than to say good tires are a critical performance part. Allforces pass through the tires, so they need to be as grippy andpredictable as possible. For street use, an ultra-high-performance tireis the ticket--track duty calls for specialized tires, such as DOT roadrace tires, or drag radials. While a big tire budget isn't necessarilygoing to change your life on the street, where so much driving isnowhere near the limit, specialized tires make all the difference at thetrack. Put another way, if track time is your plan, a dedicated set ofwheels and tires should be you first purchase, whether its drag, roadracing, or slaloms.
Brake options for the '99-'04 cars are varied. A powerful andcost-effective solution is to fit more performance- oriented brake pads,especially the fronts, and keep your pads at no less than 1/3 thickness. A step up to the Cobra 13-inch braking system or equivalent fromspecialists such as Baer or Stoptech is also a quick mover at tuningshops. Because they come painted a snazzy red with the running horselogo, the FRPP Special Edition Bullitt calipers are very popular. Theycan be mixed with aftermarket slotted rotors to come up with a dressybrake for relatively few dollars.
Another popular upgrade for...
Another popular upgrade for '99-'04 Mustangs is lowering springs. Asimple 1-inch lowering improves handling and looks. You'll need toupgrade the shocks and struts with the higher rate lowering springs, orthe car will ride like a baby buggy.
Suspension tuning comes in two basic forms. By far the most popular iswhat we'll call the upgrade approach, where lowering springs, a fewurethane bushings, and other replacement parts are fitted. Perhaps theultimate expression of this strategy is the Eibach Pro System Plus kits.Given the workably rigid SN-95 chassis, these parts provide a definitefirming of the suspension and a notable improvement in street handling. They also work well on the road or slalom course until you really starthammering. Then, they prove skittish as the limits of the stocksuspension geometry are reached.
The second approach is to essentially replace the suspension with partsfrom Griggs Racing, Maximum Motorsport, Steeda, and others. These areexpensive, no-excuse solutions, but offer truly impressive results.
There you have it, late-model Two-Valve tuning in a nutshell. Thesecars are ideal as warmed-up daily drivers--we hope you've learned a fewtricks to improving yours. And remember--have a plan and talk with yourparts supplier.