how many exhaust spacers?
 

My motors in the race boat sit low. Real low in the hull. I was going to use a 6" exhaust spacer to make up the difference but at first look I think I'm going to have to add a bit to that. Can i stack the 6" spacers like in the picture without issue? If not what do you beside having custom exhaust made that are not in the budget?

http://img10.imageshack.us/img10/8486/unled3e.jpg