I just looked at my photo album and I marked the pipes red and blue for port and starboard. Port is the odd size.
Starboard pipe:
https://www.fcpeuro.com/BMW-parts/X5...ds=34326755666
Port pipe:
https://www.fcpeuro.com/products/bmw...mm-34326752219
Prices came way down on the port pipe. I'd have bought oem prefab. They don't come bent you still have to bend them.