Putting new angle tips on my boat. I've seen they make a gasket for this installation or should I just use 4200?

Installing mine with the sealant. I think better seal with the 4200 vs gasket. Coating bolt holes also.

Using a gasket or rubber seal and just using sealant the bolt holes will make it a lot easier if you ever have to remove them.

Also any tricks for removing the old tips that have the sealant between the flange and the transom?

I used 4200.

Just hope some clown didn't use 5200. They should come off fairly easy. Use a block of wood and hammer.

Pretty sure it is 4200. It is still plyable. I guess get inside the bilge with a block of wood and hammer and tap them out?

Stick 2x4 in from inside and pry up and down a little to break the bond.

use a heat gun on the outside around the ring and a wood wedge and tap lightly with a hammer

I was thinking more of rocking them back and forth from outside with a hammer against a block of wood or like "pitts' said. They should come off pretty easy if not 5200. A little heat never hurts but you might not need it.

Just juming in to say be careful if you use a heat gun (the commercial style) because you don't want the area around the ring to get to hot.

If it does... "Pop" all of a sudden, the area will start to "blister" from the heat.

Especially if the transom is painted...