There are a host of options available depending on what you intend to spend and your desired outcome. Your 898, assuming stock configuration uses log type exhaust manifolds with downturn joints to a Y-pipe, that bolts to the transom plate and exhaust exits through the prop. Several advantages to thru hull is a slight power gain from free flowing exhaust, reduced drive temps, better sound, and possibly less weight. You could opt for a system called captains call which allow you from the helm to select thru prop or thru hull. Handy around the docks. Others have opted for placing the transom exhaust ports below the top of the drive. This allows the exhaust to be under water untill you go on plane. This is how my CVZ is configured. New center rise manifolds will allow greater flexibility to where your tips can be placed over the current logs. Another consideration is the Y pipe, unless converting to captains call with center rise manifolds, this pipe will be removed, and a cover plate bolted on. I've been told this can be accomplished with the engine in place, I'd like to see it done. Swapping exhaust manifolds is also much easier with engine out. One thing to mention, the CVZ is nearly identical to the CVX's of the period, so don't get dismayed if you can't find one for a CVZ only. I hope you find the transom solid and dry when the time comes to install your new exhaust, projects like this seem to uncover the hidden gems in the bilge/transom area.