Where did you get the headers that are on your car? They are so low, they look like headers that are for a truck with a 302. My long tubes aren't near that low.

 

You need to learn how to go over speed bumps.

either go over at an angle or gas it a bit to lift the car over the bump then slow down!

 

i had the same problem. header about same height and at every speedbump i would scrape on the ground.
my front was a bit lower though. you can always try that method with those thingies (i don't knwo them).
I got a proper set of heavy duty springs and shocks and my problemm was gone since.

so maybe check on your shocks (that;s easily done). if they're fried they'll allow the car to swing that low.
if you have an I6 to V8 conversion you might need different springs in the front

Kalli