The X150 had a resonance problem in the exhaust system which affected some but not all cars. A vibration could be felt through the foot pedals. Jaguar revised the mounting system which involves a revised clamp system - the cost from Jaguar is expensive for what you get which amounts to a couple of different clamps. Your dealer should be able to call up a Jaguar Tech Bulletin which covers this subject and the approved fix. Not sure if your year was affected but I'd push the dealer to check. I believe the bulletin number is JTB00088