best performance exhaust for 496 engines?
 

thinking of upgradeing exhaust system on my twin 496 ho boat . what system performs the best , most hp gain etc. don't have alot of room between engines so need to take this into consideration.

most people run the corsa or CMI exhaust when upgrading.

Check out Kieth Eickerts. I ran them on me 242 and they were a great exhaust! Here is a comparision of various exhausts on an HP 500. Click the arrows on the top to scroll through the data.

What are you trying to accomplish?

trying to get alittle more top end speed , figure with exhaust , and prop change it would be possible?

Take the KE manifolds and skip on the CMI headers. That way you will gain good performance if you upgrade your motor, and you won't have leaky CMI headers. For what it's worth though, it has been debated over and over. But fact is, that new headers or manifolds won't help you alone. I don't care much for it when BT says 4-5+ mph gain, I don't buy it. I know of no one who saw a speed increase over 1 mph from CMI's or other headers. But of course, when CMI pays for advertisment, you better reccomend it when you are the lead test driver.

What are the spec's on your engine. How many RPM's does your engine rev at max power?

Agree 100% with this statement. CMI will only last so long and then they will leak. The KE's will last much longer than any tude header and you'll never have to worry about leaks!

put a different intake on first...

One with a blower attached?? :lolhit:

i remember seeing a few posts on here about people having pretty good results with the Dana exhaust on 496's

i was thinking the same thing, what are good improvements to make to the 496 ho?

Sell it and get Eddie Young to build you a 650:lolhit:








There is the Raylar 103 kit, but the cast internals are not really up for the job. When you start to mod the 496's, the internals has to be upgraded as well for good reliable power.

Nearly 10 years of hard running on my 2 sets of KEs and they are still basically like new. Best marine pipe going unless you are in heavy salt and don't flush.

i've seen some dyno results,and the KE really perform good...the others give you power at high rpm mostly

Stock Merc 496? If so, save your money. The factory manifolds work very well for the application and are durable. A bud installed the CMI headers and saw zero gain in performance.

+1.

Best exhaust for a stock 496 HO? Stock aluminum manifolds. The ports are huge and capable of flowing more than the engine can give them.

Couldn't agree more. If you feel compelled, pull the manifolds off and do some minor port work on the holes and put it back on.

I think the stock 496 exhaust kit is one of the very best "stock" exhaust systems out there. It flows well compared to most (all) other Merc exhausts, the riser is stainless so it will be around forever nearly & it's a dry joint so you won't see any of the constant leaks and failing gaskets unless you neglect it.

On a stock 496, there is not a kit out there that will increase the speed of your boat solely on its own. Anyone who makes that claim is not being forth right in my opinion..

If you can not turn a bigger prop or turn your existing prop faster you are wasting your money. An exhaust upgrade on its own with the 496 will not allow for either of the two scenarios.

Better off to lab the heck out of the next size up prop and that's as good as it gets and it's usually under a thousand bucks to do so.

:coolcowboy: