catalytic converter growing worse for few thousand miles. Any danger re engine damage?? how urgent to get it fixed?? car faces inspection in Jul, '20.

What is your question?

Sounds like a hole in the muffler. Mostly from front, driver's side of car. Is it necessary to 100% replace the whole system, or just where the problem is?? Noisiest on start up; as engine idles down, noise reduces 50%.

What makes this problem better or worse?

It's worse when engine is cold; doesn't seem to affect performance; gas mileage is worse

How long has your 2009 Audi Q7 had this problem?

several months - car isn't used that much. Noise has grown worse over 2,000 mile period, or 8 months