I love my X5 exhaust upgrade.
https://youtu.be/Ug-foANeWXs?si=G5TQzWivrdpI6DRh
(Not exactly the most economical).
(This is my 2011 35i that replaced my 2001 3.0i)
I do love the exhaust note. Wife calls it exhaust therapy. I agree.
Here's another where I rev twice and open the exhaust flap for the second rev.
https://share.icloud.com/photos/0ca4...pAPL2363_ApwQw
You'd think you can modify the 3.0i exhaust to match the 35i. You won't get quite as burly of a note but the first video above is just idle and it's the same basic engine when turbo not spinning. Wonder what it would take to retrofit e70 exhaust to e53. (thinking junk yard grab).