X1 Top Speed Loss?

[NeonBullet]

I couldn't make a post in main GT5 forum (not enough posts), so I'll ask here.

Will an engine rebuild fix the X1's top speed, I have tried changing the gear ratios already. The top speed seems like its 245 miles per hour, compared to my other x1 that's 270 miles per hour. Will an engine rebuild fix this issue?

 

[Barkode]

Are their downforce settings different? Max downforce will give you a lower top speed than minimum downforce. IIRC its around 250 and 300 for max and min