my front bumper isnt that low. the very bottom of the car is though. im not so worried about the bumpers on mine. no lips on this car out on the market.
a 21st what? it doesnt really scrape, only if i try tall things. and by tall i mean things that are like 4 inches. prolly wont go over a 4 inch bump 
but like i said, the bags solve my problems with clearance plus i get to go all the way down parked.