Thanks 9250! Did u have a control in the cab to change the % over or do you have to stop and do it? My thought was half the time unloading is fine, but when I need the power I was wanting to switch it in the cab only when needed. But I'm sure once you have run it with the 15% it is hard to change it back. And also in your mind did u think you were overloading the motor by putting this on, any heating up or anything of the sort? Also I had heard that you have to change the fuel filters more often, did you experience that? Thanks again for the reply!