I was looking at that. I have zero experience with nose cones. From what I read on hear it seem that the imco cone like to be near the surface, my drives are deep. For $107 it's worth a try. How deep were your drives and what kind of boat did you run it on?

Stock X , standard length drive Mach 26 DCB, I tried an Imco lower it didn't change a thing speed wise.

This is my first boat with twins, so a lot of this is new to me. Here is another thing that happens about 63 or so and get worse with more speed. When trimmed out and WTO I need to slowly turn the steering wheel to keep the boat going straight. It can be as much as 1/4 to 1/3 of a turn. When I pull back on the throttles its a white knuckle experience, it feels as if it could hook up and dart, of course it doesn't but it is not a pleasant experience. I've always thought this was a clear sign that I needed external steering; however, the more I read posts it sounds like my drives may be blowing out. Does anyone have any input on this?

Just curious, what was the design speed of the hull ?

No idea- but I know it isn't 67 mph. There are guys with 90-91's with 502's and the modern bravo lowers and they are in the 70's. Mopower has a 272 that does over 80 mph. I'm no where near the hull speed of the boat. There is an issue somewhere, and the more I dig, the more I think its the lowers. I just don't want to spend the money replacing them only to find out it was another issue.

Good luck

I want to fix the problem. I'm sure its something simple,however knowing what to fix is the issue.

At that speed I don't think it is the lowers. My 272 is rock solid at 65. Is there any play in the gimbals? Or cable helm? The gimbals on the 272 were worn and I did not like it, i rebuilt them and good to go.

I had this exact same condition (backing off the throttles) turns out it was a bad steering ram. Every time i'd get big air and land the boat would get squirrely too. I went full hydraulic. Problem solved.

As far as slip - your tach's might not be accurate. The tach in my 1989 Mirage reads a few hundred high.

Talk to Tom at Hydromotive Props. I don't know if they still make it but they used to have a nosecone for the older Bravo One. They were designed to prevent blow out on the old style drives. Eventually Mercruiser changed the design and it wasn't needed.