Twice I've run my truck up Ranger Hill (I-20) which is a pretty good grade (I know some of you will know what hill I'm talking about) I hit the bottom of the hill 2 different times with 2 horses loaded in my trailer (see my pictures for how big my trailer is) running 75mph both times. The first time I hit running my 100hp setting and I only lost 5mph on the whole hill, the second time I hit it running the 60hp setting and only lost 7mph. I didn't have gauges running the first time and the second time I never hit 1250*. (I love my boost elbow) (I'd really love twins)