Just installed the Hypertech Max Energy Power Programmer Stage 3 tune onto a 2005 Duramax Diesel. Wow, talk about easy -- just plug and pretty much go. I think it took about 12 mins. to download into the truck. Then we were off leaving our marks along the way. You read the reviews and checked out all the clips on YouTube and your first thought is no way. I'd say those YouTube clips likely are true as well as the user reviews. I noticed a definite power increase right away. Using the Stage 3 tune the peak horse power was upped by 87 and the torque rating went up by 173 lbs.
One other more practical side benefit of the programmer was being able to program for the larger tire size that is on the truck now. Fuel mileage also went from about 10 mpg to 15 mpg, according to the driver information screen on the truck. Note, though, that we did update the CPU to the correct tire size as it has taller tires than stock. More power/torque and better fuel mileage; can't go wrong with that set up.
We haven't tried Stage 1 or 2 just yet -- who wants less than maximum power -- but I'm told that's where the fuel mileage improves more.
Hypertech Power Programmers are any easy way to get more from your vehicle while putting less into it and still maintain the factory appearance. Find the Hypertech Power Programmers at Tire Rack under Engine Tuning.
This is my personal experience with the Hypertech Programmer, it was a great investment!