its not a silverado or sierra but its a gm! haha i have a 2008 chevy 2500 express work van, got it for my job.. but just recently while it idles i hear a wierd bang noise from the front of the van, at least thats where i believe its coming from... the first time i heard it i thought someone hit my van with a wooden bat... it only happens once and a while and only at idle sitting still, and when it does happen its just one "BANG", not several in a row. i thought it might be some kind of engine backfire but i went around to the exhaust and its not coming from there.. I know this isnt the site for the express vans but i trust you guys more than anyone! thanks!