I never saw my risers sweating. I run a regular thermostat housing and a circulating pump. I do not like the crossovers.. Too many issues with sweeping water temps, condensation and cold oil temps. The river water temp where I live is 45-50 in april..

Where are you dumping the water from? The jump hose? I have the same problem with my EMI Thunders. The problem was so bad I opted to change the cam to basically what you have now. We are going to start this week and if there is reversion I am going to dump water as well. I talked with Drew as well and told me the same thing, but had no advice on where to get the fittings, so if you figure it out please post as it would be helpful. One more note, I have a friend with a 25' Nordic with a popped out 502 and a larger cam (236 @ .50, 112 LSA, 614 lift, 109 ICL) with the same Eddie Marine exhaust as you, and he has no problem... GO FIGURE!

i had this problem with a stock 502 last year, i took the riser off and ran it and you could watch the manifolds sweat water on the inside while running. im not a emi fan at all, i run stainless marine and real happy with them.

Baggmann, Drew told me to take the water from the hose connecting the manifold to the riser. I am having eddie marine make these fittings for me. You can also take it from the top of the aluminum manifold on the opposite side . There should be another 3/4 plug. I was going to take it from there with a 3/4 brass fitting reduced down to a 1/2 in. hose barb and out the boat. The problem is its a tight area to work unless you pull the risers which I did not want to do. I also ordered shotgunIII silencers which will stop the reversion by adding back pressure to the system at idle

Reversion is not always from the cam size
Check this article out
http://www.michel-christen.com/ExhaustElbows.pdf

Did you take the riser off of the stainless marine manifold and run it? Cold water running through a manifold that is 1300 degrees will sweat. Sweat is not reversion. Reversion is water creeping back up the pipe to the engine.
I can idle my boat all day with the silent choice on with no reversion. But as soon as i open them up 1 minute later they start missing and the idle gets sloppy and dies out.
Back pressure seems to stop the Resonating Reversion

http://www.michel-christen.com/ExhaustElbows.pdf

Very interesting article. THANKS for sharing!

Update: This is the first time out in 4 years with NO REVERSION problems. I have to say DREW from DREW MARINE is a genius. I bought 2 pairs of shotgun III silencers from them and installed 4 tee fittings 3/4 npt x 3/4 slip x 1/2 npt on the outlets of the aluminum EMI manifolds. Eddie marine made these fittings for me. Then I installed 1/2 npt x 1/2 brass barb fittings and ran heater hose out to 2 water dumps on each side of the boat. I opened the exhaust to the loud mode idled out in the no wake zone and WOW no load up, sounded smooth and even.Amazing..Boat ran great and seem to have more power.
Very Happy