Ok...this is a stupid question but I was wondering if these tips would work on my boat? I currently have IMCO silent choice with 4" all the way out the back. How do these tips mount? Do I need to make the 4" hole in the transom bigger? I currently have non-muffled tips with a slight angle down toward the water.

If your existing tips are like mine, the tip is mounted with screws into the transom through the outside trim ring. These tips look like Corsa's that would mount by through-bolting to the inside of the transom with a trim ring. I'm not sure if you need to enlarge the hole but you may neet to drill for the bolts.