Felt this star was improvable so I gave it a shot, the biggest issue is that Koopa's stopping position is luck-dependent (afaik based on initial interaction angle & finish time), and 95% of the time he runs right into the wall before decelerating. Even when getting that good run though, it's hard to perfectly time interacting with him while maintaining enough speed to jumpdive. Afaik the somewhat silly movement during the Koopa race matters little if at all.

This run's definitely improvable but not worth it for now. I mostly just wanted to get a decent run with the speed-conservation ending lol