I have done that -- actually had to place two of them in the exhaust after the riser/elbow; one at the top and one at the bottom of the short run before the elbow. It cured the problem of the elbow overheating and cracking. I did replace the hose with silicon high temp (the blue stuff) to further avoid any chance of a problem. The old hose had blistered big time
My 6B is 250HP. I am actually surprised you have a 6" on a 210, but then maybe i shouldn't be
The raw water pump is undersized, IMHO, and by the time the water got to the elbow it simply fell and flowed down -- no 'spray' to mix.
Now, temperatures at all engine speeds are even around the exhaust hose and within spec of the high temp fiberglass elbow on the downhill side. It was a disaster waiting to happen.
I believe i posted a pdf of the project on the board here.. do a search and see if you can find it. If not I will try to dig it up and repost.