Need so help. This is my first diesel and I want to change the sound however this truck has a lifetime power train warranty. The service manager said I could change the muffler but I had to leave the def on the truck. They also said I could put a tuner on it as long as it saved the stock information. Do they make a kit for this and if I don't buy a tuner right away will it throw codes. I might sound stupid but I really need some help with this.