There are two different levels of dry exhaust. Both are ridiculously loud.

Fully dry is jacketed tails that are closed at the tips and have a water dump welded in that dumps the water overboard through a thru hull fitting. You will have no chance of reversion this way.
Dry to the tips is a jacketed tail that is open at the tip so water mixes behind the transom. Very little chance of reversion. My tails are dry to the tips and I still get water back to the collectors at idle, none in the oil. My cam is a good bit bigger than that one though.

Just to point that out.

Lightning Dry Jacketed
 

That is what I was told by someone else as well. Thanks for the other info too on the alternatives.

Updated my project page in the Velocity section. Had a big day moving the boat but a highway near disaster! Thankfully the project is on!