Ok, summer is winding down here in PA.  My thoughts are moving toward upgrading the exhaust
on my CV 23 during the off season.

Does anyone know how the upward style manifolds compare to the long bolt log manifolds flow wise?  I can't use the extreme headers without rebuilding the back of the boat.

 Here's a picture of my boat engine in the original configuration to give you an idea what space I have to work with.  I can do some mods for more room but I don't want the sun deck messed up.  That would bring on the wrath of my wife,  and that ain't gonna happen.

I need something water cooled and compact.  I'm considering GM style with adapters.

What I don't want to do is spend $$$$$ on new manifolds that won't flow any better than the long bolt logs I have now.

 Would it do any good to cut off the rear of the riser to go with the larger exit hose and tips with the long bolts?

Do you know where I could find info from anyone that has done dyno tests with different brand Ex. manifolds?

I've been kicking this idea around and now that the engine is done its time to help it exhale.

Thank you all in advance, any input will be greatly appreciated.

It's not that I don't want to spend the $$  I just want to make darn sure I'm making
a big improvement when I do it.

I don't want to spend the bucks to move backwards.   That's where I'm hoping your experiance
comes in.  You'll prevent me from wasting my time and money.

Yes that setup was how it came from the factory.   The temps were around 160 to 170 early in the season and 170 to 190 late.   The problem with it was the temp would spike when dropping off plane and you would have to cool it back down.   

The jet inlet came to the water pump cover at the top.  The front line was to let water into the manifolds when the thermostat was shut.

The other problem this boat had was the thermostat would snap shut as soon as the cold lake water started through it.  It caused the engine to over heat.  That is how I bought the boat for $6500 brand new.  The dealer had the block freeze in an early cold snap, they had the block replaced and couldn't get it to run cool after that.

I bought the boat and tried it out.  I could hear the time bomb ticking so we pulled out the thermostat.  Problem solved.  So I don't know if there is a special marine thermostat but this one had a car type and that was a big mistake.

Here's a picture of what we are running now.  I had to switch the front plate when going to the
long tubes.  This setup on our boat has much more stable temps than the old system. 

I had to go to them to run the stud girdle.  You will NOT have a rocker come loose
with a stud girdle.  I doubt you'll ever break a stud either and I wanted to make sure our paddle
was never used.   

from what i was told lightings you can keep your hands on them at all times, and supposed to flow really good

Have any of you ever opened up the risers on your logs?   I'm wondering what if any good would
come of larger exit hose and tips.   With the stock tips it's less than 3" opening.

Next question is the edelbrock heads exhaust port is shorter than the log opening.  I'm wondering
if port matching them with the logs would help or hurt.

That's about the only improvements I could see possible from the long bolt and riser setup.

What do you guys think?