I used the Dana cast aluminum manifolds and made over 1700 HP. They worked very well and there's nothing to leak.

CMI headers that were of the original spec for Mercury are the issue.

CMI makes better headers, but that's not what Mercury spec'd for OEM. THAT is the "CMI issue". CMI gets the bad wrap, but it's all Mercury's fault.

I don't fully blame CMI. I've read of a bunch of manufacturers headers who leak. It's inevitable. When they do, bye bye motor. I'd take less bling for better reliability.

I know any exhaust can fail at anytime. It just seems headers fail frequently.

Get the Stainless Marine GEN III setup.

X2 CMI's are a bad design and make less power.

Is a good guy, but they only sell cmi and imco.