Second year in a row I get problems with my Y-Pipes, below is the picture of what pretty much happens to them. Mechanics replaced both Y-pipes last year with same problem that looks like below (I paid sh*tload of money to replace both Y-Pipes, as engines had to be pulled out). This year week after putting boat in the water same problem with port Y-pipe happened again. What can be the cause of this corrosion/holes in the Y-Pipe? Obviously mechanics can't make a good job preventing this from happening since this is happening second year in a row.