What's the difference in headers and manifolds
 

Well I'm going too redo my 454 in my boat and I want too upgrade the exhaust. I saw emi makes aluminum manifolds and risers for my application because my boat is salt water cooled and staying that way. I also saw they make factory manifolds aluminum with a coating on the inside and a 5 year warranty for about 800 bucks complete kit. I've also seen headers with water jacketed which I don't quite understand yet and can't see how they would work on my boat? Can someone explain these setups and how they work thank you

Headers have separate runners for each cylinder. The benefit is it creates a "scavaging" effect. With a plain old 454 save your money and go with manifolds.

Save yourself a lot of money and bunches of headaches. :-)

http://eddiemarine.com/emi-thunder-e...ig-block-chevy

I've been looking on eBay and people sell used headers and used manifolds and stuff too help with cost and most of them say fresh water use. It's a mild 454 build I'm doing and the manifolds need replacing so just trying too see what's my
Best bet and thank you I've been looking at the emi thunder setup

Don't buy used exhaust unless it's brand new "take-off" stuff. Take all freshwater only claims with a grain of salt. Especially if the parts are located near an ocean! The EMI stuff looks good. I put $4,000 CMI headers on a 496 mag HO and saw ZERO performance increase. I drank the Kool-aid ...

If you are bent on spending some money, I would buy Stainless Marine exhaust. I replaced the CMI's on my 525efi with SM and the performance didn't change.

I rather take the cheaper way out. Don't really need stainless. I don't keep the boat in the water and I flush it out after everytime I use it and I plan on upgrading too another boat in a few years maybe more. But for now with the new mild 454 going in thought I spend a litttle more then the 850 dollar factory aluminum manifolds I can get and get something with a little more flow.

Stainless marine is the company name. They make aluminum manifolds. Arguably the best performance manifolds on the market. Designed if they fail to fail externally and Not internally to destroy the motor

Stainless Marine manifolds are not made out of Stainless Steel. Do you have Silent Choice? Make sure you buy the longest risers you can in case you plan to do upgrades on your 454 in the future.
http://www.diamondperformanceparts.com/home.php?cat=274 Eddie Marine
http://www.diamondperformanceparts.com/home.php?cat=272 Stainless Marine

No I don't have silence choice and I run corsa mufflers on it but I make quick runs with my boat so noise doesn't bother me especially since I came from drag racing too boats. I'll have too get a picture of my current setup tomorrow so you can see what I have before I dismantle it.