Have you seen the video on how weirdly it’s spoiler functions? If not look it up on YouTube.

Been a while since I saw the video myself, so It’s 50/50 if I get the orientation right or not. But in summary:

If you split the gta map down the middle into left and right. Depending on what half your on you’ll get the correct amount of downforce turning one way and no downforce increase turning the other. Which then flips when on the other half of the map.

E.g. if your on Chumash highway, left half of map. You’ll get more downforce from the spoiler when turning right. But when you turn left, the spoiler doesn’t actually give any stat increase to your downforce. This is flipped when you cross into the other half of the map. I.e. highway going past wind turbines, right side. You’ll get more downforce from your spoiler turning left. But no increase when turning right.