6s are much heavier than the 3s.
Will screw up the boat's COG if the boat was built w/ 3s originally.

The shaft sizes are the same and there's twin verticals like 6's. Actually, internally I never understood the difference between a 3a and a 6. 3a's were always referred to as baby 6's i ran the **** out of my 3A's on my gun in the Pacific Ocean in big water. I never stressed zinging the drives while airing the boat out. It was very comforting knowing I had those drives hanging off the back. I think the 3a's are rated to 800hp and the 6's are rated up to 1200 ???

I hear this cog issue over and over again, how many apaches have 6's on them? And how many were actually built with them?
Take a 37 outerlimits stilletto for example, same bottom, same cockpit and cabin layout but you could buy the boat with side by side bravos, stag bravos, side by side 5's stag 5's, stag 6's or triple bravo, yet no one complains the cog is screwy.... Unless something is WAY off like a 28 saber I know with the fuel tank behind the rear seat and a Konrad ace on a box i have yet to see a major cog issue.

Ujd, all I know is I had spent sometime w/ Magnum Mark and he had mentioned this to me.
I consider him to be one of the most knowledgeable and experienced, especially on Apache's.

I would think getting it back to the US and registered could be a task? Not sure how that works and why is there no pics of the engine comp? Makes me wonder, other than that it's cool.

on a tank like the 41 apache i wouldnt think it would make a bit of difference

the center of gravity makes a big difference on an apache. if it wasn't built as a 6 boat then there is substantial work that needs to be done to make it preform/ work properly. what i was told is if it was built as a 3 boat then leave it as a 3 boat. i have spoken with mark m. on this topic and i would think he would know.

So what was changed on island racer? Anyone have pics of these substantial changes or is the cog all screwed up on it? It was built before the 6 drive even existed wasn't it?

Just curious here, are we talking about a really well setup race boat or a pleasure boat? I would think that changing a small percentage of overall weight on the transom would not have that big of an effect, then again, I have no experience to base this on.

14,000# boat (rough guess)
500# change in hardware (rough guess)
=3.6%

I guess that number is bigger than I thought, but still, will it upset the boat?

Shouldn't it be looked as Force(mass) x Distance. So being the drives are most furthest aft that small amount of drives can have a significant change due to the distance from the CG. I am curios how the boats where set up differently. I imagine the main difference would be fuel tank location. I wonder if there where any other levers that could be pulled..... Engine location?