Apparently there is a lot of flex between chassis and body due to body mounts. This means if there isn’t enough clearance between aftermarket bumpers that are bolted on to the chassis and the front fascia they will certainly interfere going over bumps.
If the bumper is flush with the body it would most certainly cause problems down the road. If you look at raptor, bronco jeep steel bumpers there is huge clearance between body and the bumper to mitigate this issue
