Idleing.

At idle, a cam with a big lope and overlap will suck water back up the tailpipes.

Would a "silent choice" in the on position prevent that from happening?

Actuallly it makes it worse

It can happen when you pull back on the sticks to fast, It can happen when that wall of water comes back at the transom when coming off plane. It is most common at idle speeds.

I guess if the overlap was really extreme it could happen at WOT, but you would need a lot of duration.

Cam shaft selection is an art form. I leave it up to better trained profesionals rather than trial and error. There is to much money at stake.

I run that same set up its a 420 454 bored 60 stroked with dart intakes and lightning headers its awsome.

If you are running silent choice, then you definatly have the wrong exhaust for a performance cam. Ditch the silent choice and go with long risers, or dry pipes. I use the EMI thunders, there are a set for sale in the swap shop. Looks like a good deal.

Nevermind, I see that was somone else asking about silent choice.

I have rubber connecting the tips to the riser, prolly about 12 inches or so. I will try to post up pictures.

What do you guys think?

I am not familiar with those exhaust. But that does not look like a dry pipe system to me. If that is a wet exhaust those risers are to short. It does not look like it is set up correctly to me.