Is now in SR repo (
here).
I added some new things:
Changed light to even more strange (black specular, white shadow).
A small cave for variation and 3 surprise barrels in that bumpy straight, also 2 waters there and color height fog.
Another 3 surprise barrels in pipes up.
Added 1 more pipe material and pipe wall. 1 more grass only lower.
Changed that high up turn so it's driveable reversed too (this matters
).
View doesn't show much change: