Ok so the exhaust has now been on the car 300 miles and seems to be bedding in quite well. At first on tick over and pull away it was very burbly but had a tinny ness to it. This tinny sound seems to of disappeared.
The discolouring issue seems to be short lived too as once I used AutoSol on it the gold never really returned as quick or as dark.
The power aspect seems to be improving too, feels a lot more sprightly 3rd gear and upwards. The bark I can defo still feel (under drivers seat strangely).
The rattling bolt issue will be sorted ASAP as I can hear it still on tickover.
So as I said, it's only been 300 miles but the sound seems to be evening out a lot more. The ECU seems to realise there is a different exhaust on there now, but as I have the 3" TIP and forthcoming big FMIC I better not leave it too long before I go stage 2 as I'm asking too much of the car with so much efficient air/gasses going through a generic stage 1 map.
I will also add that there is a slight drone now from the exhaust from 40-60 in high gears but this is to be expected.
Will update when I've done 1000 miles and stage 2 power.
Sent from my iPhone when I should be working....