I think MT has been fooling us all along - that really IS his pink broom, and that's MT in the avitar posting on OSO!

I think the slip joint sucks. Literally.

These are not the standard Lightning headers most are used to.

You know, you are probably dead on with what you are saying about a lot of motors having some water getting back in. Friend of mine has nearly the same setup on his boat - Lightnings with the separated collectors and HP500 cam - yes, more aggressive than mine, and he has been running his for years. He was curious if he is getting any water in his as well, and was even talking about snaking a tube in there to see if there is any water sitting in there. (you are probably thinking OMG - Budman's rubbing off on him! Just what we need, another epic thread about Lightnings with tubes being shoved down them. )

I agree - definitely not optimal. They were my only real solution without having custom tails made or filling in and re-cutting my exhaust holes in my transom. Boat was originally small block.

I don't like the way they introduce the water either. I think a couple of those holes on top need to be blocked or redirected, and maybe dumps added to take some of the excess overboard.

I typed 2 paragraphs, asked myself YYYYY, deleted them and decided to commit suicide instead.

Why you worried about the idle? With such a mild hyd roller, I wouldnt sweat it. I have quite a bit more cam than you, and sometimes on the lake I have to idle for 30 minutes to get back into the harbor/dock.

I know not to check oso tech section from my phone, if I am standing on the edge of a cliff or roof top. Chances are Budman will have a new thread full of concerns, that are very likely to make a guy wanna strap banana peels to his shoes and hope for a gust of wind.

Best wishes on your trip to the afterlife, Brian. Don't take any wrong turns!

OK guys, I guess I'll just chuck this thing in there this weekend and not worry about it, even though the headers were WET all the way back to the primaries when I ran it on the stand a couple days ago. I mean, what's the worst that could happen? A few ounces of cold water on those hot exhaust valves after a hard run will be good for them, right? Quench harden them!

Pull 1 header off. Position it as same as on boat. Hook up water and see if it the header design alone that allows water to run backwards , taking the motor out of the equation.
From your pics I can see how water coming out of the holes can splash hard enough to get some to go the wrong direction. The water needs a way to be redirected rearward. Just a 2" length of pipe tack welded to the inner pipe would be enough to get the water moving the right direction. But then this assuming I'm seeing the pics right. Kinda hard to see from my end. The holes appear to be just straight into the pipe, not pointing rearward