who makes the better exhaust manifolds,want to upgrade from stock.will i really see any performance gains with aftermarket manifolds or should i go with headers?want to keep my silent choice

There will be many many different views on this subject. If you're racing you may want one type. If you're just a performance boater you may want yet another.

One important factor for me is life. Tube headers probably won't last near as long as an aluminum manifold and stainless riser combination. There may be some difference in top end performance and maybe not. My Stainless Marine aluminum manifolds and long stainless risers do not leak, make good power, look nice ( to me anyway ), save weight, do not pass water through a joint, and may outlast me. They have been pretty much a thing to install and forget about them. That is until the hatch raises and you see the nice stainless tubes. A manifold/riser combo may also be a little easier fit in some boats and seldom if ever requires any hatch modifications. I honestly believe that even if I had a cruiser type boat I would install Stainless Marine exhaust for the extreme added reliability and improved performance. There are other similar types from other manufacturers that work well and live long. I just happen to like the Stainless Marine best.

I realy like the way tube headers look and sound but I appreciate the infinite reliability of my combination more. Mercruiser uses a lot of CMI product. That's obviously a good product. Still, the manifold riser combo will outlive it.

Do a search in the archives and you will find a ton of info/input, and reading on the aftermarket exhaust subject.

When I was shopping for performance manifolds back in 1992 there were few and far between choices. There were a few companies making BBC parts but no one made SBC exhaust parts. I bought Glenwood HP powdercoat aluminum manifolds and Fastglass powdercoated stainless 4" smooth short risers. They have proved excellent quality and are still going strong 15 years later. Sadly I don't believe either company is still in business.

They provided a nice performance increase especially when the AFR heads and cam went on.

This says a lot as better exhaust is just part of a system; by itself, upgraded exhaust may not be worth the investment for a preformance gain in the 0-2 MPH range.

Well said. Exhaust alone will do little, if anything, to your performance. If you have made cam, head and intake mods or changes from stock you can expect decent gains with tubular headers. For most stock applications manifolds are more than adequate.

That being said; a set of polished stainless headers looks GREAT under the hatch but be aware that they come at a cost. Reliability however is NOT one of them. A good set of stainless headers (if properly cared for) will last as long if not longer than cast manifolds.

We sell RMI cast aluminum manifolds that work great in most stock applications and are great deal at the price.

We also have good deals on Lightning Stainless headers for those who have motors that can benefit from a good scavenging exhaust.

Just remember that no matter what exhaust you choose, if you drain your exhaust after you run, you will greatly increase the life of your exhaust system.

Good luck with your decision and I would be happy to help if I can.

Fionn

As I understand it, a true header (with 32 - 36 in. primaries of proper ID) will generally yield some noticeable performance gains on a stock BB. Will the gain be as much as the manufacturerers claim ?? Hhmmmm.... I think that's a discussion for another thread LOL.

Given the cost of a true SS header system, is the cost worth the gain ?? Maybe so, if at some time in the future there are plans to mod/hp the engine. But IMHO if the engine is to stay stock, or only mild mods are to be done to it, I'd say a decent after market aluminum manifold/riser will be just fine. After dropping a ZZ502 in my boat, and after doing some research a few years ago, I bolted on polished aluminum Revolution Marine Exhaust. There was a noticeable mid range gain, limited WOT.

Now I'm in the process of having some substantial mods done to my ZZ502, and have a KE Exhaust to bolt on, which is also aluminum So if anyone is interested in a good used Revolution Marine Exhaust system, let me know

I am getting ready to replace my manifolds and based on the research I have done, its narrowed down between EMI, GIL or Stainless Marine. SM has a good reputation but I don't know if they are worth $700 more than the Gils or EMI's. Anybody want to chime in?

One seldom talked about advantage is the servicabilty. Headers are easier to take on and off inside the boat. I can hold a header with one arm while I put bolts in with the other. It's also allot easier to change spark plugs. You can actually see them.

i am thinking about emi also,if i spend 2 grand this year on manifolds and end up supercharging next year will these be ok or am i gonna have to step to cmi headers.only want to do this once