Hey, all. I'm having a bit of a conundrum with some knock and funky ticking/ fluttering sounds on my 6.4. Last year I got some Kook long tubes and catless mids installed, along with solid motor mounts and a nitrous kit (which I really haven't used) and installed an email tune from a reputable tuner. Shortly after, I went on a work trip for about 8 months that I came back from about a month ago. Before I left, and about a week or 2 after I got back, the car drove and sounded great with zero issues. Then I started to see some consistent STK on my Trinity. Anywhere between 2-10 degrees between 2000-3500ish RPMs. At first, I went to the fuel as it had a quarter of a tank that had been sitting for a good while before I topped it off with fresh BP93. Still got knock, so I drained the tank, filled up with Sunoco 93 and a bottle of Royal Purple octane booster with no change. The car is making a a fluttering/ ticking sound, but only under acceleration and again, at 2k and up. We found a header bolt that had backed out quite a bit, so we tightened it back down and checked torque on all the bolts, but didn't see any soot deposits or any visual signs of a leak. At the same time, we did an oil change with Amsoil and an SRT filter. The car STILL makes noise and still picks up knock while driving and in neutral, albeit a little less. Also a weird thing to note, if I Rev in neutral and let off at around 4-5k, I can hear a pretty noticeable whoosh of air, almost like a turbo blow-off, so I'm still optimistic in thinking there's an exhaust leak somewhere the sensors are picking up. The only thing we haven't tried yet, short of opening up the block, is a stetho or smoke test. I'm hoping someone here has some input that can help me in the right direction before I start tearing into things I don't need to as I know longtubes are pretty notorious about resonating engine noise you normally wouldn't hear or notice. Thanks in advance!