hey rrbgtt welcome to the forum! I've heard many of people getting not so good mileage the the first several thousand miles with their diesels when they are bought new, not just the PSD's. So just relax and give it some time. Believe it or not, you could see a pretty impressive gain alone by getting a complete turbo-back exhaust kit. It'll help mileage, power, egt's and get rid of the heat quicker which will help your turbo out quite a bit and probably extend it's life. Plus it is not a modification that can do any damage to your engine or transmission or anything on your truck. The worst damage it does is to your wallet...about 400+ depending on what you get for it. But it's a cheap and common diesel engine mod and very well worth it.