The Duramax 6600 diesel has a lot of untapped potential - just waiting to be unleashed. We've finally tested the latest performance module from Diesel Services Group for the Duramax 6600 that adds more capability to an already strong running powertrain. Teaming up with Van-Aaken Developments, DSG has developed a Duramax performance module that maintains important powertrain safety features, such as transmission slip protection, while delivering a smooth boost in towing power and awesome street performance.

Key Features:

• Quick & easy plug-in installation.
• 3 convenient switch-selectable power settings - stock, +70 hp and +110 hp.
• Does not raise fuel-rail pressures.
• Monitors engine and transmission speed to provide additional slip protection.
• Lower smoke levels and exhaust temperatures, compared to some performance products.
• Smooth, fuel efficient vehicle operation.

Unlike some of the early Duramax performance products that increased fuel-rail pressures, the DSG PowerBox provides for an impressive power gain by remapping the fuel and timing curves. Fuel-rail pressures are left untouched. These remapped fuel and timing curves also produce a beneficial increase in boost pressure. Start-up and idle control remain unchanged for easy starts and typical off-idle driveability. An optional in-cab 3-position rotary switch provides for OFF (stock power), +70 HP, and a "light your tires" +110 HP position. Power settings can be selected "on the fly" with no objection from the vehicle computer.

The included installation guide covers most aspects of the relatively easy installation quite well. Installing the optional in-cab 3-position switch could take the most time, so we'll cover that portion of the installation here in more detail.

The 3-position switch, wiring and electrical connector come fully assembled, with a generous wire length that should match just about any sort of installation. However, being assembled with a connector on one end and a switch at the other makes it a little difficult to pass the wire through a firewall grommet without making a big hole. What I did was cut the wire, which required a much smaller slit in the firewall grommet (located to the left of the brake master cylinder). Crimp connectors could be used to reconnect the two wires, but I chose to use solder and shrink tubing once the wires had been routed inside the cab.

The wire leads are not polarized, so getting the same two wires reconnected is not an issue. The switch provides for direct continuity in position 1 (OFF), 2.71K ohms in position 2 (+70 HP), and an open connection (no continuity) in position 3 (+110 HP).

Once you remove the nut and lock washer from the switch shaft, the locator pinwasher could shift out of position. This is a semi-generic switch that can provide more than three switch selection positions. Just make sure the pin is inserted into the #3 position to limit the switch to a total of three selectable positions.

The switch shaft length will likely need to be shortened for your installation. I used a vise and hacksaw after determin-ing the length I needed.

The 3-position control switch was installed at a convenient location on the bottom rim of the dash, directly in front of the driver. You'll need to enlarge one of the existing holes using a 3/8" drill bit. Once the switch has been installed, push the round knob onto the shaft, and tighten the setscrew against the flat on the shaft using a 5/64" Allen wrench. Turn the knob counter-clockwise to decrease power and clockwise when that Dodge is trying to pass.

The switch location I chose is but one of many possibilities. Some owners flinch at the thought of drilling holes in their dash panels, and wish to maintain a stock appearance. The location shown here is about as unobtrusive as they come, yet maintains easy access.

After having spent some time with the DSG PowerBox, I can see a number of advantages over some other performance products available for the Duramax 6600. It is obvious that the PowerBox has been in development for quite some time and is now a mature product. Owners will surely appreciate the smooth power delivery and low levels of black smoke. Aside from the impressive power gains, vehicle driveability remains refined and smooth no matter which of the three power settings are selected. Lastly, being able to select between the three power levels while driving makes the DSG PowerBox an excellent choice. And yes, it'll light your tires in level 3!

TDP

Postscript: The DSG PowerBox is now available in a higher power version - stock/+90/+158 HP. Our dyno tests with the high-power version produced a gain of 142.2 horsepower above stock.