The exhaust came on the engines already in the boat. I am planning on building two new engines (496's), so new exhaust is not in the budget (I’m already WAY over budget)

If you have ss long risers their rated for 700 hp..Do you know how old they are?When you take them off remove the riser and see if theirs coolant passages between the riser gasket and the top of the manifold,if their are none their the newer style,if they have the holes have then welded up and run the bypass hose to the riser..I know guys running 540's with them and are vary happy with them..

I was running them on my 572ci SC with 900hp no problem I would say they are good for 800 HP and lower.
Very good manifold

I run them on 500HP. Make sure you have long risers if you plan on a performance cam. Call RMbuilder when you do your engine build, he will set you up with a cam and valvetrain that will blow you away.

I am running them on a 540 with 700hp and I am not having any problems

I had them on a 468 with a 731 cam and captains call. No reversion problems at all. If you run any more cam than that you should have the long risers.

Thanks guys. Yes I do plan on changing to long risers.