i have an issue with my EP3 that is really bugging me. I bought it about 5 weeks ago and it had a decat pipe fitted but with the original cat supplied. So a week later I had the cat re fitted and all was ok for a few days. Then there appeared a rattling noise which occurs at low revs, about 2k to 3k (ish) and generally when the engine is under load. Once I'm out of that rev range the noise goes and all is well.

now I know what you might be thinking, it must be the drive shaft heat shield or maybe the cat heatshield which is what I was thinking. So today I had the car up on stands and then removed them and whilst I was under there I gave the cat a bit of a bang with the back of my hand and there was no rattling or knocking coming from inside it so I thought all was well. I lowered the car and took it out for a spin and the noise was gone. After a 10 minute drive I came home and went out again about half hour later and low and behold the noise is back again.

Im now getting really annoyed at what it could be as I also took the manifold plastic cover off just in case it was that but it wasn't. The rattling is at its worst if I try accelerating in too high a gear so when the engine is trying to use all of its torque if that makes any sense. Does anyone have any ideas on this please as it's driving me up the wall as to why it would come and go like that?

Without seeing the car and just going on what you're saying, it sounds like a typical knackered CAT symptom.

But as I say, this is only going on your description.