Yeah, no course in any Mario Kart game gets me quite in the zone like Toad's Turnpike. Constantly drifting between and around cars, knowing when to slow down or when to use a certain power up, I think it's the most fun level in any kart racer I've played. Actually takes a consistent effort just to stay in good position.
I'll take some reworking of the blue shell. That'd be great. Maybe improve AI instead of rubber banding them since a lot of people hate that or something.