This is a job well done! i didnt try all the levels (or tracks) but the levels (or may i say tracks) are very speedy so this map (or track) pack is for the ones who love just speedin across ramps and loops
The levels themselves are pretty fun gameplay wise, and actually feel like they're designed around speeding through them lap after lap. I really like how you used zoomtubes for rails in speed highway, and that speed booster fling part. My biggest problem with them is that visually they kinda feel like final demo maps. Maybe try using more modern textures, more slopes, that sorta thing? Or if modern equivalents to the textures don't exist in the base game, take a look through the community asset pack, or try making your own?