Hey everybody need some help I've already been to 3 different shops with no resolve. I recently went stage 3+ on my 2015 STi. I already had Invidia Catless Downpipe and Corsa Exhaust installed. Everything was fine. I then had Tomei UEL Headers, Grimspeed Uppipe with Tial 38mm EWG installed. Now for some reason I'm getting a ticking/ratting sound that's coming through my downpipe. It happens at any rpm, even idling and only goes away when I get the car really hot. If I shut the car off to get gas, when I restart the car the ticking sound is back until I drive around for at least 5mins. If I do a pull the sound goes away. So for some reason it goes away with heat. I thought it was an exhaust leak but I've been to 3 subaru performance shops with no success. My slip joints on my header dont leak, they checked the gaskets with water and soap, all good. So I'm confused because it goes away with heat, I would think whatever it is, its expanding with heat and sealing the leak? I've done tonnes of research and cant seem to find this issue with heat. I've heard of people saying that the headers or up pipe could be causing the ticking/rattle because it's thinner metal but why would it go away with heat? It's also louder coming from the passenger side but its definitely ticking in the Downpipe. What you think? Need some ideas.
Any help really appreciated. Thanks in advance!