Sorry dude, I don't know squat about exhaust systems but for dirt, I recommend going organic and maybe making your own mixture based on the finding of some experienced growers such as Subcool. He has this awesome organic soil mixture here: http://www.rollitup.org/subcools-old-school-organics/338384-2010-revised-super-soil-recipe.html
You could also order soil/anything you need online to be delivered to your place
You could also order soil/anything you need online to be delivered to your place