Boss Suspension - Over The Top

With the stock gear out of the way, Steve installs the Steeda rear springs and adjustable perches together. This clever billet adjuster allows the replacement spring to fit on the stock location, while still allowing for ride-height changes.

Steve pre-routed the ducting from the front fascia scoops to the back plate, but before clamping it in place, he trimmed a bit of the metal wire endoskeleton from the end of the house to ensure a tight seal between the hose and backing plate.

The factory Boss Brembos are pretty great, so Steeda stuck with them on this build; Steve just reinstalled the factory stoppers.

Out back, Steve removed the factory sway bar, Panhard bar, springs, and shock absorbers.

Steve rounds out the rear Adjustable Suspension System by installing the infinitely double-adjustable Tokico D-spec shocks.

Don't think this is just a spring and shock upgrade. Here Steve removes the NVH-centric stock lower control arms.

While the Steeda Billet Lower Control Arms (PN 555-4405; $279.95) are certainly stiffer than the stock pieces, they feature polyurethane bushings, so they retain streetable levels of noise, vibration, and harshness. Here Steve applies grease to the bushings to make sure the stiffer bushings don't squeak.

After removing the stock upper control arm and its mount (one fastener must be accessed below the rear seat), Steve bench-assembles the street Adjustable Third Link (PN 555-4112; $179.95). This link allows for complete adjustment of the pinion angle, but Steve starts by adjusting its length to 8.36 inches, which is a bit shorter than the stock 8.48-inch length. The chassis side of the mount must be torqued to the factory 129 lb-ft specification, which is best achieved outside the car with the mount clamped in a vise.

With the upper arm installed in the mount, Steve reinstalls the mount and torques the arm to the rearend housing. Once the car is at its final ride height and the suspension is bearing the weight of the car, Steve will use a magnetic angle finder to set the proper pinion angle. Steeda recommends between 2 and 5 degrees down.

After bolting on the Steeda's billet caliper mount, Steve installs the ABS sensor in the new bracket.

In order to install the Steeda 13-inch Rear Brake Upgrade (PN 555-6009; $539.95), Steve drains the rearend fluid, removes the differential cover, pulls the pinion shaft, pops out the C-clips, and slides out the rear axles.

Post axle removal, Steve unbolts rusty stock caliper mounts. The rear upgrade kit also features braided steel brake lines, which will require bleeding the brake system.

The new bracket relocates the stock rear caliper to the proper spot to accommodate the new 13-inch DBA rear brake rotor. These larger, vented rotors should shed more heat; they certainly do a better job providing an appropriately sized backdrop for larger-diameter wheel packages.

Supplanting the factory Panhard bar is Steeda's Watt's Linkage (PN 555-2525; $1,049.95), which does a superior job of eliminating lateral suspension motion. Because the Panhard rod is fixed at rearend on one side, it will move with the suspension, while the Watt's remains steadfast. Additionally, the Steeda Watt's offers an adjustable rear roll center to precisely dial in the handling.

The rugged, chrome-moly Watt's mount bolts to the chassis, while its rearend attachment points clamp securely to the rear axle tubes.

Next up, Steve installs Steeda's Adjustable Rear Sway Bar (PN 555-1073; $384.95), which offers three levels of a stiffness adjustment. The billet end-links and polyurethane bushings also firm things up a bit over the stock parts. It was necessary to move up to Steeda's top-shelf gear to out-do the robust Boss LS gear.

When Steve bolted on the billet lower control arms, he also added Steeda's Lower Control Arm Relocation Brackets (PN 555-8119; $141.70), but these must be welded in placed once the chassis is loaded with the vehicle weight. These brackets are necessary to restore proper instant-center geometry on a lowered Mustang.

Steve returned to the Watt's with a digital level to adjust its linkages so they are parallel to the pavement. A proper adjustment ensures that minimum of lateral movement in the suspension.

Returning to the front, Steve once again called on Steeda's big-gun Adjustable Front Sway Bar (PN 555-1070; $208.95) to upgrade the Boss' front-end grip.

Remember those beautiful HRE wheels we showed in our lead photo? Well, Steeda does all of its own mounting and balancing in-house. Here Steve mounts the Nitto NT05 rubber on the forged wheels. These beauties measure 20x9.5 inches up front and 20x10 in the rear, and wear corresponding 275/35-20 and 315/35-20 Nittos.

After mounting the wheels with black locking lugs (PN 182-71683NBC), Steve performs a performance alignment on Steeda's computerized alignment rack.