955 Engine Noise

[Zac-Man79]

Hey all, first post here. I have an 06 Cayenne S that has developed a concerning noise on cold starts. I went out to start it this morning and it had a light thudding noise from the engine. It's not quite a ticking or metal to metal noise, more like a deep thumping sound- loudest in the driver side wheel well. I've searched the interweb on the illustrious bore scoring videos and I don believe it's that- or at least I hope not!  Definitely a lower pitch and not a tick. Only happens on cold starts and is correlated to engine rpm. The sound gets better as engine temps increase and not noticeable at all once it's reached operating temp. I can start it anytime with the temps above 150ish and no sound. No CEL and no change in fuel mileage so I'm hoping this won't be a huge PITA to diagnose. My first thought goes to spark plugs or a stopped up injector but a misfire or at least a code would have showed up right? I'll be sure to grab a video when I get a chance but wanted to post to see if anyone had ideas or things to check first.