Exhaust Valve Rattle after Iroz Dp installation

[captainhaggs]

My shop installed the Iroz downpipe a few days ago and when i was picking my car up my mechanic told me that after he installed and started the car he noticed a pronounced rattling coming from the exhaust valve. I noticed it immediately when pulling away, it is a distinct tinny/metal on metal noise coming from the left side exhaust. He says it may have been an preexisting issue that i would not have noticed before, but now with higher flow its glaring. Im wondering if he caused the issue and what are options to fix this issue so I have something to off of next time I speak to him. Assuming he had some responsibility in causing this, as i have never noticed a valve rattle before this installation, what should I expect from him and what should i be prepared to pay for replacement parts?

Thanks guys,

[allerum]

Audi has a new part number out for the whole back of the exhaust, not sure what it is but also sometimes rocks get stuck in the flap

[captainhaggs]

looks like it wont be an issue, my mechanic has a friend in the service dept at my dealer who says hell get it warrantied with the dp