Hi all, Started a new thread now we know a bit more about this issue. So as you know we have a metalic noise from the loose exhaust valve pivots. This is a given, Audi replace backboxes for this. We have a cold start Tick / Rattle which can be hidded by starting in Dyamic or mapping it out and we know this is to do with the start up cycle and is normal. For us with a Decat, we get the cold startup rattle / tick all the time. In a nutshell we have had custom decats, Miltek, Scorpion so we know its not them. We now have 3 different back boxes, Miltek, Scorpion, and Audi and they all still have this issue. But closer investigation shows this is coming from the front of the car. Alot of suspicions are the Wastegate. So the noise is always there its just not aparent with a cat and the decat exhibits the noise, or does the change in pressure cause the noise? What resolutions do we have so far: 1) Put original cat back on (thats just ****) 2) Try a sports cat? (expensive option) 3) Try and get Audi to look it as a fault? - They may just say - put the cat back on. So completely ****** off with this car now. 56k and cant even stick a decat on it without it sounding like a bag of smashed hammers. Rant over. Anyone else with any insight feel free!.