Congratulations on your upload, I look forward to the future upgrades, and adding more stars.
With regards to the brightness of textures, I see most of your objects have a shader value of Ambient 0.5 and Diffuse 0.6, whereas most tracks generally values of around 0.2 or 0.3.
I did an experiment and created an extension config, and even though a lot of texture files are very light (for example very bright concrete textures) I was able to get it looking a lot better with a reasonably bright PP setting using values of:
PROP_...=ksAmbient,0.75
PROP_...=ksDiffuse,0.05
PROP_...ksSpecularEXP,5
I don't think these are ideal values but they made everything adjusted look a lot nicer with a PP exposure setting that works well on all the top quality tracks.
Maybe worth considering adjusting for future versions so racers can run the same PP filter settings they use for their other tracks.