The Pacbrake C40007 is a 4-inch inline-mount PRXB (Pressure Regulated Exhaust Brake) kit engineered for 2003–2007 Ford F-250, F-350, F-450, and F-550 Super Duty trucks equipped with the 6.0L Powerstroke diesel and 5R110 TorqShift automatic transmission. Built with a heavy-duty ductile iron housing and treated with Pacbrake's proprietary Arcor salt-bath nitride coating, this assembly resists wear, seizing, and high-temperature corrosion under severe duty conditions. The PRXB system features an external spring-controlled pressure-regulating mechanism paired with a 90-degree non-contacting butterfly valve. Unlike standard fixed-orifice brakes that lose stopping power as engine speed drops, the PRXB regulates backpressure dynamically, delivering up to 50% more braking power in the critical 1,400–1,800 RPM driving range while safeguarding against engine overpressure.

Terrifying brake fade on long downhill grades, glazed service brake pads, overheated rotors while hauling heavy fifth wheels or equipment trailers, and transmission converter slippage that bleeds away retarding force are what this complete kit eliminates. Standard factory Tow/Haul mode and stock VGT turbo vane retarding provide inadequate holdback when gross vehicle weights approach maximum ratings. The Pacbrake C40007 commands maximum permissible exhaust backpressure throughout the RPM band, while the included transmission controller ensures the 5R110 torque converter stays locked during deceleration. This direct mechanical lockup routes continuous braking horsepower through the drivetrain to slow the vehicle, extending service brake pad life by up to 300% to 500%. It is sold as a complete turnkey system, including the inline PRXB brake valve, transmission/throttle controller, and an AMP onboard air system (HP325 compressor, 0.5-gallon air tank, and 25-foot coiled auxiliary air hose); aftermarket 4-inch exhaust adapter pipes (C11342 / C11400) are sold separately for trucks running non-OEM exhaust tubing.

It fits 2003–2007 Ford F-250, F-350, F-450, and F-550 Super Duty trucks as well as 2003–2005 Ford Excursions equipped with the 6.0L Powerstroke diesel, 5R110 TorqShift automatic transmission, and factory exhaust tubing (manual transmission models require kit C40010; trucks equipped with an aftermarket 4-inch OD exhaust require adapter kits).

Fitment

• 2003–2007 Ford F-250 Super Duty 6.0L Powerstroke (5R110 Automatic Transmission)
• 2003–2007 Ford F-350 Super Duty 6.0L Powerstroke (5R110 Automatic Transmission)
• 2003–2007 Ford F-450 / F-550 Super Duty 6.0L Powerstroke (5R110 Automatic Transmission)
• 2003–2005 Ford Excursion 6.0L Powerstroke (5R110 Automatic Transmission)
• Fits factory exhaust systems (vehicles with aftermarket 4" OD exhaust require two C11342 adapters)
• Engineered specifically for 5R110 TorqShift automatic transmissions
• Patented PRXB spring-regulated mechanism delivers 50% more braking power at lower RPM (1,400–1,800 RPM)
• Arcor salt-bath nitride coating prevents internal carbon seizing, galling, and rust
• Includes electronic transmission/throttle controller to lock the torque converter on deceleration
• Complete onboard air system included: HP325 12V air compressor, 0.5-gallon air tank, pressure switch, and coiled air hose
• Turnkey exhaust brake and pneumatic management package

Park the truck on a solid, level surface, set the parking brake, and disconnect both negative battery cables. Measure and mark a 7.25-inch section along the straight run of intermediate exhaust pipe behind the transmission crossmember, verifying clear clearance around fuel lines, wiring harnesses, and the driveshaft. Cut out the marked section cleanly with a reciprocating saw or pipe cutter, deburring the inside and outside edges of the cut pipe completely to ensure smooth exhaust flow and prevent gas leaks. Slide the exhaust pipe ends into the Pacbrake inline housing flanges, orienting the casting so the exhaust flow direction arrow points toward the tailpipe, and clamp the Marmon flanges firmly using the provided V-band clamps. Mount the HP325 air compressor and 0.5-gallon reservoir tank to the frame rail using the included bracketry, routing nylon air lines to the pneumatic actuator cylinder and 12V air control solenoid valve. Under the hood and dash, connect the electronic transmission controller harness inline with the factory PCM and transmission connectors to command torque converter lockup during braking. Route the throttle position switch harness so the butterfly valve disengages immediately when the accelerator is depressed, mount the in-cab toggle switch on the dash, reconnect the batteries, and road test the vehicle under closed-throttle coasting to confirm instant exhaust retarding and smooth converter lockup.