I installed my dana marine exhaust into my Donzi. The tips are about 1.5" narrower than the risers and the 12" run of wire reinforced 4" exhaust hose is really at it's limit of stretch. I had to use 3 people and a 8 foot 2x4 to get enough leverage to get the riser twisted straight to sit down in the manifold! I'm dreading doing it again.

Does anyone have something more flexible? I was thinking high temp silicone or similar.

Not much is going to stretch more than Good rubber hose.

Be careful, my buddy's scarab had that problem and he burnt the hose out on the bend. He had to have some custom bends made out of stainless.