So I've read a few places online where having a liquid propane gas kit on a cummins 12 valve will help increase mileage by 2 or more mpg. I've also read on here that running LPG can give increase power output by a little bit. But I've heard that running LPG can decrease power output by about 10%. Are there any others benefits to running propane? And who makes a propane kit for a cummins 12v? Is there a real cost effectiveness to this since youll run both diesel and LPG at the same time?