No this is not true.. You do not crash in the corners. I played the hardest stage with the cheat on right to the end, I had machine guns blasting the whole time, had turbo kept on the whole time, I used the cheat number "10" & "10", I was able to turn every corner at 324k/mh without touching a corner.
This is the screen where you type in 10 & 10 on numeric pad
I think it would be great to have it added as I had more fun with it enabled.