Hello folks, I bought the AquaTunePlus unit for my ’04 GMC Denali, 6.0L after a bunch of guys and I had been talking about it at work. So, I got to be the “guinea pig”. Boy, am I glad I was ‘cause I got every bit of the 25% increase and more. I figure I gained probably 32-35%, depending on my driving. I also bought this unit to help keep my engine clean internally. There’s something else I wasn’t expecting, but I’m sure glad, and that’s the increase in the horsepower. I might also mention, that the system was extremely easy to install. Your support service is excellent and so is your product! P.S. – My brother says he’s going to be ordering one shortly and I hope his results are as good as mine.