Answering a few of the questions above.
- I haven't taken it on a road trip yet. Driving around Houston highways (60mph - 80mph), if you pay attention to the exhaust sound, you can tell it's a little louder. But with anything on the radio, or at higher speeds with road noise, it doesn't sound that different from stock. It's there, but not annoying or intrusive.
- Diffuser is off of eBay. Not sure about the trailer hitch.
https://www.ebay.com/itm/14406035757...sAAOSwOFpgti9T
- Yes, tips are the brushed chrome LeMans tips. Will coat them satin black at some point, but not in a rush. Plan to enjoy the slow mod.
- Install went smoothly other than needing to make a small trim to the new diffuser. Tips are just a hair too wide, so the shop had to cut a little from the edge of the exhaust cut out.
- Agree with beyondm3, there's only one version on the IND website. Update: reached out to confirm with IND. Eisenmann only offers one version for the M550i (in the U.S. at least), the valved sport version.