Hello, long time listener, first time caller.

Building a Merc 496 HO (I know, I know), was leaning toward Raylar of course as there aren't many other options.

The issue I am running into is finding a suitable exhaust available prior to Spring time, nothing is in stock......supply chain issues. 🤣 CMI is 8 mos out and Dana/MIW is just hoping on about a month but nothing yet in production.

I would like to get the boat in the water as soon as the weather breaks, so this leaves me with either finding a suitable used exhaust for sale or running the stock manifolds until I can get a suitable replacement performance manifold/header.

Sooooo, now that I may need to run the stock manifolds I am limited as to what camshaft I can safely use without a reversion issue. This could potentially restrict max possible horsepower potential. I'd hate to limit myself, and/or pull the motor a second time just for a cam swap nine months later.

So, my question is, what is the biggest issue with reversion when selecting a cam? I assume camshaft lobe separation? I was told that the min separation should be about 112 degrees? What is the consensus on this? Can I get say 600HP @ 5100-5200RPM with 112?

Larry at Raylar did not recommend the camshaft provided with his 600HP kit while running the stock manifolds, so he is steering me toward the safer option of the 525HP cam.

Long story short, I want the best HP potential camshaft that I can temporarily run stock manifolds with.

Could the stock risers be modified longer and water introduced further back? I have a good straight shot out of the boat to work with.

If anyone has some exhaust options for me, or a lead on where I can get newer used, please let me know.

Thanks in advance!

Stainless Marine.

Maybe post some pictures of your exhaust to see what your options may be

Any good used options out there?

Maybe, eBaycmi marine headers for sale | eBay

"Maybe post some pictures of your exhaust to see what your options may be"


That was my plan, I have a good pic, but as a new guy I cannot post an attachment yet. Its pretty straight forward, stock manifold to stock 8" header, maybe 18' of rubber then exits transom with a Eddie Marine Big Can muffler. Will post pic when able.

I have been all over Craigslist, Marketplace, and eBay. Only one nice CMI set around but they are +6 so that's not gunna work. The 496 E-Top CMI is what I'll need.

Good idea! Yeah thought of Stainless Marine right after my post. I'm thinking worse case scenario I pay for custom extended risers. Phone call in, message left.

They make a great product and great customer service. I had a set of gen3 made for my 540

I have these Gil's. manifolds are new pipes are used but nice but are dry to the tip but do have mufflers welded in the pipes. 3K for all plus shipping