New here and this is my first post. I currently have a 1994 GMC Yukon that I recently picked up. I have searched and read many post about the OPS, LP and the relay mod. I am pretty sure how to begin this task but I do have a few questions. If you look at the 2nd picture you will see how I plan to wire up the relay to the lift pump. Where I get confused is in the 3rd picture. What is this LP relay shown here for (had to borrow the pict) and will my relay mod hook up before or after this relay. I was planning on cutting the wires to OPS about 3 to 6 inches back from the plug to the OPS. One other question I have is with the thermostat. Some say 180 is better than the 195. Some say the fuel mileage will be hurt using the 180. I am reading so many different stories. I am running the 180 stat and before I switched it from the 195 my truck ran just fine before. Now I changed it about a week after I got the SUV and my current mileage is around 14.5 mpg. This seams pretty low since I don't tow but some say it could be cause of the winter diesel. Any ideas why it could be so low? Thanks. Thanks.