Loud banging sound from underneath

What is your question?

The banging noise is only when driving and giving gas going down the road if you let up on the gas and cost it stops soon as you let off but when given gas the faster you go the faster and louder the banging gets. I have look at all the heat shields and stuff that may become lose and rattle or bang I have found nothing . Please any clue is a +

What makes this problem better or worse?

It is worse going down road giving gas but stops when not giving gas

How long has your 2007 Hummer H3 had this problem?

2 weeks or so and just Happened all of a sudden