Headers
 

Whats the difference between water jacketed headers and water injected headers?? is the jacketed ones on the outside and injection ones spraying water on the inside??

Jacketed is a tube within a tube. Water completely surrounds the hot exhaust tube. Used in enclosed engine compartments with most I/Os. The jacket keeps the exhaust cool.
Water injected is a simple tube header with a small amount of water injected near the cylinder head. These can still get very hot. Commonly used on smaller boats with over the transom headers. These CAN NOT be used in an enclosed engine compartment.
My $0.02
Gary

gary : nothing to add perfect description.

hyper : i use injected type in my boat.they are much cheaper.but my personal idea is they are more for hot-boat type show boats or lake boats.water injection tubes are so weak,has to be to protect engine from back-water.i dont believe you can use them more then 2 seasons in salt water.
got mine from rewarder headers,excellent finish etc...but still not good for off-shore..

Tim,

I would be very careful running the injected headers on your boat. I have seen the pictures and it looks like you are looking for trouble. The water injected headers still get extreemly hot. Maybe hot enough to burn fiberglass as close as your hatches are to them on your boat. They also need to have the water restricted at idle so you wont injest water into the engine. This means at idle there is no cooling water at all running through them. I had a jet boat with a 429 Ford in it with water injected Basset headers and the headers would glow red even with the water running through them at full throttle. You couldnt see it in the day but in the evening on the way back to the landing you see the red plain as day. Be careful.

Ron