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USD 1607.05
Part #: PBC44045

Pacbrake C44045 DirectMount PRXB Exhaust Brake

2004.5-2007 Dodge 5.9L Cummins (Manual) | 2006-2007 Dodge 5.9L Cummins (Automatic)
Part #: PBC44045
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Pacbrakes flagship product, the PRXB (pressure regulated exhaust brake), is the unquestioned leader in the supplemental brake industry. The patented PRXB design delivers the strongest braking horsepower, greatest speed reductions and shortest stopping distances possible without the use of service brakes. It maintains optimum retarding performance by maximizing the exhaust backpressure throughout the entire RPM range. Unlike a typical exhaust brake, which requires high RPMs to work properly, the PRXB delivers constant exhaust pressure (braking) as early as 1200 RPM through to the maximum allowable RPM.

Controlled by a master ON/OFF switch, Pacbrakes exhaust brakes provide whisper quiet supplemental braking that allows service brakes to be used much less, ultimately saving you money. They have the ability to be left on all the time, making it ideal for in-city driving or for steep, downhill grades. This product pays for itself as less wear on the brake pads means fewer brake jobs.

  • For Use On Stock Turbocharger
  • Less Wear & Tear On Service Brakes 
  • PRXB Delivers Strongest Braking Horsepower
  • Ideal For In-City Driving Or Steel, Downhill Grades

In order to have consistent and effective braking over the entire RPM range, it is important (and necessary) to maintain constant backpressure. To achieve this, Pacbrakes patented design has incorporated an additional waste gate on the butterfly valve to regulate the amount of exhaust flow that is being passed through. The flow is controlled by a spring-loaded arm, whose pressure rating and location are key factors in the functionality of the PRXB. Located outside of the housing and away from the heat, the spring is able to maintain its strength and durability for years of proper and precise braking performance.

Backpressure is created by exhaust flow entering the housing, hitting the closed butterfly valve and being forced back out in the direction it came. It is maintained by the pressure-controlled spring that is located on the outside of the exhaust brake housing.

As the engines RPM increase, the spring compresses and the arm moves away from the butterfly valve, therefore releasing more exhaust flow through the orifice. As the RPMs decrease, the spring releases and the arm applies pressure back onto the plate, covering the hole, and ultimately releasing a smaller amount of exhaust flow.

There is less than a 10% change in backpressure over the entire RPM range on the PRXB

Shipping Restrictions Apply shipping restriction icon This product can not be shipped to these states: CA

Vehicle Applications

2004.5 Dodge 5.9L 24V Cummins
2005 Dodge 5.9L 24V Cummins
2006 Dodge 5.9L 24V Cummins
2007 Dodge 5.9L 24V Cummins


  • MFG. Number C44045
  • Manufacturer Name Pacbrake
  • Shipping Weight 35.00 lb.
  • Shipping Length 18 in.
  • Shipping Width 17 in.
  • Shipping Height 10 in.
  • Fuel Type Diesel
  • UPC 628480001012
  • Prop 65 Prop 65 WarningWARNING: Cancer & Reproductive Harm -
  • Internal L5.00R5.00


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Questions and Answers

Does this kit contain all parts required for a functioning brake including compressor?
View Staff Answer 
Yes, The Pacbrake C44045 DirectMount PRXB Exhaust Brake comes as a complete kit including the compressor.
I have already added a 5" MBRP exhaust system, will this still fit?
View Staff Answer 

Yes it will fit. The exhaust bake utilizes your factory V-Band flange and turbo mounting points.

Does this product come with a computer that talks to the trans and the ecm?
View Staff Answer 

The Pacbrake C44045 DirectMount PRXB Exhaust Brake comes complete with the harness for wiring the system into your truck.

I have a 4 inch turbo back mbrp echaust on my 2005 dodge cummins manuel. Will this work and what diamiter is it?
View Staff Answer 

Yes, it will fit. The exhaust bake utilizes your factory V-Band flange and turbo mounting points. Roughly 3.5" in diameter

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