[Brucelee]

I recommend that you:

Have the car aligned by a quality shop.

Have them do a thorough inspection underneath. If you hit the curb at speed, I suspect you have some damage, even if it is just an alignment issue.

Enroll in a qualilty driving school.

Stop trying to show off when lives are at stake. If you want to risk your own life, that is your call. Your friend might take exception to risking his.

Good luck.