Lifted & Tuned GMC Sierra vs the Ike Gauntlet: World’s Toughest Towing Test (Video)

gmc sierra 1500 bully dog tuned
(photo: TFLtruck)

Can a lifted and modified truck retain most or all of its factory towing capability? We put this lifted and BullyDog tuned GMC Sierra 1500 on the Ike Gauntlet, world’s toughest towing test, to find out the answers. Can this truck “tow like a bro”? Find out in the video below.

Most of us like to customize and modify our trucks. However, trucks with big suspension lifts, large wheels, and other accessories become heavier and more sluggish. This is where tuners such as Bully Dog come in.

The truck you see here is a 2018 GMC Sierra 1500 with a 5.3-liter V8 under the hood and an 8-speed automatic transmission behind it. It’s a crew cab 4×4 truck with over 63,000 miles on the clock. This truck has been around.

The 5.3-liter V8 does not have a good reputation for heavy towing, but this engine has not let us down during our towing tests over the last 6 years. This V8 has been a base engine in all full-size GM trucks and SUVs. There are millions of these engines on the road.

This GMC Sierra 1500 also has an 8-inch lift in the front, 6-inch lift in the back. It has a performance air intake and a free-flowing exhaust system. The Bully Dog BDX tuner aims to add some power and torque, and also turn the truck into a more complete package.

The tuner allows you to permanently disable cylinder deactivation (aka. Active Fuel Management or Displacement On Demand). The tuner allows you to adjust the speedometer for the new tire size. This truck is running on 35-inch tires.

Bully Dog also adjusts the transmission response and shifting schedule in order to make it more immediate. After about 10 days with this truck, I can attest that this is indeed the case.

For this Ike Gauntlet towing test, we hooked up a 8,200 lbs trailer to see the downhill/uphill performance. We tested a stock 5.3-liter / 8-speed auto truck a couple of years ago, and we can use that stock run for comparison here. The stock truck was towing a 9,000 lbs trailer. We had to use an 8,200 lbs load for this test in order to stay within all weight ratings (GVWR, GCWR, and f/r GAWR).

On the way down, we counted 10 brake applications in order to maintain the legal 60 MPH down the 7% grade. This is exactly the same performance as we had with a stock truck.

On the way up, the truck still ran a benchmark 8-minute run – basically maintaining the 60 MPH speed over the entire 8-mile distance. The truck-reported fuel economy was better than the reported economy for the stock truck.

In the end, this lifted and modified truck maintained the overall towing performance of a stock truck with the same engine/transmission.