HiTek manufactures a one piece stainless exhaust header design that takes the place of the multiple components that comprise our marine exhaust systems. The headers do not handle antifreeze, just seawater, so they are devoid of any block off plates to fail as have done in my situation. Additional advantages include a significantly cooler engine compartment, less plumbing to fail, a major weight savings, and a performance gain (on my 454's).
With the system only handling seawater, I found the engine bay to be notably cooler. I have been flowing cooler seawater from my rebuilt heat exchangers through the exhaust as opposed to hot engine antifreeze through the stock manifolds. The engine room temperature difference is impressive on the hottest of days, making it tolerable to work (albeit I have A/C in the salon they are located underneath). The headers are also significantly lighter than the stock exhaust weighing in at 14 lbs each (compared to well over 100lbs per manifold/riser/elbow ea). This means they can easily be installed by one person in a tight spot, as opposed to two mechanics required to install the outside manifolds straining to line up the heavy, awkward setup while they bolt it on (I have 2 engines and the outsides of the motors have about 2 inches between the exhaust and the fuel tanks). Performance was also a factor, as the larger header tubes are less restrictive than stock.
The cost of the headers landed was just over $4000 (approx $1000 apiece). If you were to consider the cost of replacing the elbows with OEM parts (not aftermarket elbows), you’d be looking at $400-500 w/ labor marina dependant. That is, at best, a five year solution. If you keep the boat for 10 years, it is recommended the FWC manifolds be replaced with the elbow change. You have now exceeded the one time cost of the headers. The other scary reality is a premature failure of the stock cast iron system. There are MANY posts of this happening to boaters, and taking out engines when it does (happened to me as well). This solution solves that problem. The only routine maintenance is to check the zincs every three months like you would your heat exchanger and U-Cooler.
IF you look at the other positives for this lifetime exhaust solution, I believe the average boater will agree that they are in fact an excellent exhaust solution.