I love exhaust systems and there is so much to learn about them. I’ve built a fair few mandrel bent exhausts on my own vehicles, on all sorts of cars/engines.
Cammy/high comp and stock old school 4cyl/6cyl petrols
Turbo 4cyl, xr6 turbo. Cammy/high comp auto v8 twin system.
Old turbo diesel 4cyl.
I recently helped a mate install a 3” exhaust with no mufflers at all on his dpf equipped triton. I had no experience with dpf cars and presumed this exhaust would be quite loud.
Went for a test drive.
I THINK I could tell some difference in sound from stock.
As far as being auto. Modern ish turbo diesels don’t sound too bad, nothing like like the older stock Petrol 6cyl autos that have that horrible P plate sound.