I have a 2007 5.9 that has been making a ticking noise for some time now but has gotten worse lately. Best way I can describe the noise is an exhaust leak but we have pressure tested the engine and can find no leaks anywhere. I have put new injectors (due to a starting issue, all 6 tested bad with high return pressure) new fca, and new rail pressure sensor on with no change in the sound. The sound starts around 1600 and goes to about 2200 rpms. As soon as you mash in the clutch or let off the accelerator (take the load off the engine in any way) the noise instantly goes away. Not throwing any codes. The truck has 100 horse injector tips, smarty TNT, afe cold air intake, banks high ram intake horn, valair dual disk clutch, and an air-dog 150 lift pump. Any help would be GREATLY appreciated it's about to drive me crazy!!