I have a set of angle tips I am going to install on my boat. What sealant/ caulk do I use to install them I have been told 3-M 5200 and
3-M 4200 ? What 1 is better for heat and stays flexible? I read both packages neither says for exhaust use.

When I installed my exhaust tips (5 or 6 years ago) I used 5200. It's holding up just fine. Be sure to completely coat any exposed wood in the transom before bedding in the tips. The heat at the flange is not enough to cause a problem with the caulk.

I'm sorry but have to disagree. Do not use the 5200 the stuff is way to strong for that type of application. Use the 4200.

Yea like scott said, 4200. The 5200 is for "never to be removed" stuff.

I used the 5200 last year for my tips. Both in the 4" thru hole, and a small bead around the outside right behind the trim ring. I decided to check and reseal 2 weeks ago. The trim ring came right off with no damage, and the old 5200, while still sealed between the tips and the hull, could be removed real easily with no damage to the gel. So, the 5200 was not as permanant as led to believe. And yes, parts were clean and it was 2 weeks drying time before splashing. I did go with the 4200 this time thou. Don't want to push it.

Silicone is not a good sealer for this purpose. While it may seal at first, once it looses adhesion, it will not reseal. Unlike the 5200 or 4200.

I just put a set of angled tips on my boat a couple weeks ago and I used some stuff called Life Caulk. You should be able to get it at any marine store. It's meant for sealing metal to fiberglass. It works above and below the water line and it stays flexible. I used the same stuff on my drain plug on my old boat and never had a problem with leaks...