Suggestion:
the extra straight on FE and the short part of the straight next to the chicane on BL1 are very bumpy. it would be nice if they were even, so you can go full throttle over there, without flying high.
Anything else has already been mentioned, like missing walls. Still mad there's actually a complete track available on south city (hidden) but you cant drive there. some walls could be removed in the highway/hairpin section, as you can add nice left/right turns there aswell.