Just had a good look under the car, turns out my engine rattle is being caused by a bracket that holds the exhsut to the engine block (part 46809275). Annoyingly, I only replaced this bracket about 2 months ago. However it looks like either the manifold has bent, or the section that bolts onto it (the bit with the 2 cylindrical bits, stage 1 cats?) because the part of the bracket that's still attached to the exhaust has moved towards the back of the car by about 10mm.
This is probably why the bracket has broken, but to get it all that far out of shape I'm sure I'd have had to ground out somewhere and I think I'd know if that'd happened. There appears to be no damage to the engine block where the manifold bolts on, and the welds in the manifold all look ok.
What are the chances that the whole lot could just be pulled forward again? The only other option is replacing parts... the Alfa parts cost over £700 for this exhaust section, mainly because of these 'cats' that have sensors connected.
I'm wondering if it's time to get the Supersprint 'Manifold Stainless steel For first Kat.replacement-keep main Kat'...
...but as that takes out the first 2 cats, how would my emissions be effected? Would I need a remap? Would I still pass an MOT? How much would this screw over my warranty?!
Questions questions question, I know, but this might end up getting seriously expensive
Hopefully it can all just be bent back into shape..