flattening

I get this 'gruphf' kind of sound going over big speed bumps at 5mph. It sounds like someone stomping on a paper box or something. I don't remember hearing it before. (I've had this 03 for almost 4 years). It sounds like scraping almost. It is coming from my front passenger wheel well area. Is...

it comes with a inward curve. Those that have used it to make a grill, how did u get it to be flat?