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SKU #: GDP-030767-Main GDP Mega-Rail System 03-07 Dodge Ram 5.9L Cummins 030767-MRS

$1,444.15 $1,699.00
Glacier Diesel Black Friday/Cyber Monday Sale: $254.85
Purchase GDP Mega-Rail System 03-07 Dodge Ram 5.9L Cummins 030767-MRS
    • 2003-2007 5.9L Dodge Ram Cummins
  • Options
    Intercooler Outlet Size
    Intake Manifold Color Options


This kit is the way to fuel that fire breathing 5.9L you're building with Bosch certified parts. The GDP Mega-Rail System! The Mega-Rail System includes everything needed for installation of the enti ... read more

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This kit is the way to fuel that fire breathing 5.9L you're building with Bosch certified parts. The GDP Mega-Rail System!

The Mega-Rail System includes everything needed for installation of the entire fuel rail system from the larger 6.7L applications onto the 5.9LCummins. This simple bolt on package gives the 5.9L Cummins an edge in airflow and fueling like never before. Finally you can get the most from your modified injection pump and performance injectors!

Using our Mega-Flo Intake Manifold, Air-Boss 67 plenum and factory Bosch HPCR parts we have created a package that is reliable, easy to install, and out flows any other parts combination on the market. If you're pushing the envelope on 5.9L Cummins performance the Mega-Rail kit can fuel it.

The GDP Mega-Rail System is a complete package and does not require additional parts to be purchased. For those customers who would like to supply their own rail, lines and crossover tubes we offer the Mega-Rail Installation Kit.

  • This conversion kit eliminates the factory grid heater.
  • Only for single CP3 applications.
  • If your truck is a 2003-2004 with APPS, you will also need the GDP APPS relocation bracket. If you're unsure if your truck has APPS, please contact us.


Through the course of installing the Mega-rail System we have come across a few things that you may find useful.

First is the rail pressure sensor. With minor electrical connector modification, the stock 6.7L rail pressure sensor can be used on the 5.9L trucks. Due to voltage mapping differences the stock 5.9L rail pressure sensor reads roughly 13% higher than the stock 6.7L sensor at the same voltage. This can be used to your advantage if you are careful.

By using the 6.7 pressure sensor on the 5.9 you can raise rail pressure approximately 13% without using a pressure box. For example, at WOT this equates to 24,860 psi actual at an ECM reported 22,000 psi. At idle reported pressure would be 5000 psi with actual being 5,650 so the difference is very small. At a reported cruise pressure of 8000 psi the actual would be 9,040 psi and this small increase is good for mileage. Since rail pressure is in essence "fooled" you will need a 6.7L rail pressure gauge connected directly to the sensor to see actual rail pressure readings.

Now, for the warnings and disclaimers...

Use the 6.7L rail pressure sensor at your own risk! Do not use the 6.7L rail pressure sensor if you are running a pressure box! If your tuner of choice has a rail pressure adjustment setting we recommend running the tuner at the "stock" pressure setting. Most tuners increase rail pressure to some degree. When combined with the 6.7L sensor rail pressures can get out of hand quickly. When using the 6.7L sensor always monitor actual rail pressure with a standalone 6.7L rail pressure gauge such as the unit offered by ISSPRO.

Next up is the grid heater. There has been some talk of using the stock 6.7L grid heaters (with the Mega-Rail kit) on the 5.9L head. The stock 6.7L grid heater will NOT fit the plenum opening of the 5.9L head without modification to a small casting area under the plenum cover. It can be made to work but minor grinding will be required.

We always recommend using new parts when working on the HPCR fuel systems. However, if you are looking to save some money, there are many sources for used 6.7L rails and injector lines. Wrecking yards and core supply shops have good inventory levels of used 6.7L parts now and can save you some money over buying a brand new rail and lines. Using a Mega-Rail Installation kit and a used rail setup is a great way to make big power on a budget.


  • ManufacturerGlacier Diesel Power
  • MPN030767-MRS | 030767-MRS-59
Benefits of the Mega-Rail System:
  • 50% increase in fuel rail size - Perfect for modified CP-3's
  • 50% increase in fuel rail feed line size - Matched to rail size
  • 50% increase in injector line size. Handles even the largest injectors
  • 50% increase in crossover tube size - Removes the final restriction in the CR system
  • 3000 psi higher relief valve pressure - No need for rail plugs, we leave the safety in the system
  • 110% increase plenum entrance area - Over double the air entrance area at the plenum
  • 20% larger intercooler piping - 3.50" Intercooler piping and intake manifold vs. 3.00" stock
  • 100% Brand new Bosch fuel rail, injector lines and crossover tubes - No concerns over used or modified parts
  • 100% Bolt-on installation - It doesn't get any easier than this!
Mega-Rail System Includes:
  • Mega-Flo Intake Manifold
  • Air-Boss 67 Billet Plenum
  • 3.50" Intercooler Pipe & Boots
  • New Bosch 6.7L Fuel Rail (No Rail Pressure Sensor)
  • New Bosch 6.7L Fuel Injector Lines
  • New Bosch 6.7L Crossover Tubes
  • CP-3 & Rail Return Line System
  • Rail Pressure Sensor Extension Harness
  • Dipstick Bracket
  • All Required Hardware & Gaskets


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Rate GDP Mega-Rail System 03-07 Dodge Ram 5.9L Cummins 030767-MRS

Reviews may be edited for spelling or grammar inaccuracies and those containing profanity will be removed.

Installed this on my 05 Ram 3500 after OEM fu...
Installed this on my 05 Ram 3500 after OEM fuel system failure. All I can say is AWESOME!!! The throttle response is amazing and the continuous power at all ranges of RPM is mind blowing. I coupled this with an Air Dog II, BD Injectors and an Industrial Injection pump, and cannot say enough about the amount power I have. Hit 75mph in no time and I have to watch myself now!! Thanks Josh for all the patience and help!!
Great kit easy to install and great performan...
Great kit easy to install and great performance.
Verified Buyer
Great product and Great Customer Service
Installed on my 2007 5.9. Really high quality with everything you need to install. It comes with good instructions and the customer support from GDP was out of this world when I did have a question. Recommend the product and highly recommend working with GDP!
Store Reply
Thanks so much for the review and really glad the Mega-Rail was a solid investment. Great way to improve airflow and fuel flow.

With this kit can i get the mega-flo s-2 intake manifold so i can run the grid heater or is that an additional charge??

I would to double check with the manufacturer. But we should be able to do that for an additional 349.95. -Sands


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GDP Mega-Rail System 03-07 Dodge Ram 5.9L Cummins 030767-MRS

GDP Mega-Rail System 03-07 Dodge Ram 5.9L Cummins 030767-MRS

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