How much room do you have from the end of your riserto your silent choice I would weld stainless extensions onto the inner exhaust portion of your risers. Sometimes a few inches can go a long way.

fountain35,silent choice and eddie marine manifolds are the worst for reversion.i know you don,t want to hear that but it is what it is.silent choice and your cam will revert at low rpm,s.believe me,it is not condensation,sorry,

I ran that cam in a hopped up 454 mag with Imco exhaust and never had an issue.
I've even recommended it to a lot of people for an upgrade over stock. Its close to the 420/525SC cam specs.
I did have the longer risers and no silent choice.
I had the idle set around 900rpms if memory serves me. It was long time ago.

I would do a leakdown seeing as how the exhaust is off . If the valve seats pass now your on the road to buttening it up and not worrying about it -truely not worrying about it .especially with what looks like a street car cam grind .

Doesn't reversion cause some kind of idling issue. I had a problem and few years back with idling in loud mode. It would seem to load up quickly, start missing idling out of the no wake zone and I would have to rev it up to clear it out BUT.....if i turned on the silent choice (quiet mode) the missing, loading up would stop and she would idle normally. I then spoke to Drew marine and they told me to add water dumps to my exhaust just before it gets to the short riser. I made up custom tee fittings for this and ran 1/2" lines from each exhaust out the side of the boat. There was plenty of water still coming out of the risers. Drew marine said (quote) I don't care what cam you have and what pipes you have, If you do not want reversion dump the water. I also purchase 2 sets of shotgun silencers, not for noise reduction but for adding some back pressure. That was it !!!!. Problem solved!! I can idle in loud mode all day with no problem. No load up, no missing, etc. So maybe, after doing the above what Drew marine suggested my problem went away 75%. So those rust spots are only about 25% of reversion for about 3 years now. Maybe i'm still getting a slight mist of moisture not causing any idling issues with this new setup. My heads have been on the boat only 3 years. Does this make sense to anyone??

it does.a lot of boats have minor reversion and never know it.

I guess i'm going to have to bite the bullet and get rid of the silent choice. I just bought one set of EMI 111 long risers .I don't want to ruin another set of heads...I need another set of EMI 111.

Thanks for the input

My rear spark plugs would be wet, even a day later. Thats one way to see how bad it is.

appreciated...silent choice is coming off and i'm having the emi pipes extended

good move.