Michigan Dealers?

Howdy y’all. I have a really bad cat smell coming into my car when I run it hard. I also have a strange sound on the drivers side that sounds like a metallic scraping noise. It seems to go away when you start driving, but it’s there at idle when the engine has warmed up.

First dealer I went to for this (where I bought my car) was Tom Holzer Ford. They initially tried to tell me I was shit out of luck due to my aftermarket exhaust. I explained I think it’s a pre cat issue, please go drive it for a while and beat on it. They did. No smell. No sound outside the car.

Flash forward to this week and we got a heat wave! My car stank most of the drive home. Any time I downshift and aggressively pass it smells. So I’m thinking it was just hidden back last week when it was colder and snowing. Maybe snow and salt and crap masked it. Maybe cold temps masked it. Not sure.

I want to take it to a dealer who is mod friendly and will respect me as a car enthusiast. No bullshit service guys who will come on a drive with me and do right by this problem. Suggestions??? Only mod to my engine is the catback exhaust so I don’t want people threatening me with “we can’t help”