The cone insterts into the pipe for positioning before the welding is done. Call titan to find out how far up.
In a perfect world you want the bottom of the hole you drill to be at the top of the solid section of the cone so water can drain out. If you go up to high, you will have a water puddle and if your boat is stored where it freezes it could crack the tube. If you drill it to low you are going into solid stainless and will need lots of drill bits.