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I run the small block version.Stern drive/rec.ski boat.

Edelbrock heads 400hp give or take.
I have not had any problems for going on five year use.
Whether they are as good as Imco or others I don't know.
If you aren't looking to squeak out the most power I would run them.For the money they work.
 

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Anyone run these before.....and how do they compare to others?

454 502 Mercruiser Chevy Exhaust Manifolds Cast Iron Aluminum Hi Performance
Those are aftermarket copies of the stock Mercruiser OEM exhaust. Mercruiser uses them on all of there V8 I/O and inboard engines. In my opinion they are less restrictive than the traditional log manifold with snail. There are other versions on the market that tune the exhaust better if you are looking for more performance - at a higher cost.

Doug
 

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On a carbed 7.4 I installed the GLM's and an airgap intake and picked up 200 rpm over the stock. It also lightened the boat by 100Lbs.
 

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On a jet boat, I heard these rock. For some reason only jet guys are into these.

No, they DO NOT complete with the driver side deflector. Thats extra, but available at any Home Depot
That is to funny!!!
 

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Discussion Starter #9
All original mercruiser 454 mag. Just wondering if they are close to IMCO or others without the price tag.:confused:
 

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All original mercruiser 454 mag. Just wondering if they are close to IMCO or others without the price tag.:confused:
They are a copy of the OEM Mercruiser manifold. It is highly unlikely you will see any improvement over the stock Mercruiser center riser manifold. If you want the performance of an IMCO or Stainless you need to pay the price.

Doug
 

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Discussion Starter #11
They are a copy of the OEM Mercruiser manifold. It is highly unlikely you will see any improvement over the stock Mercruiser center riser manifold. If you want the performance of an IMCO or Stainless you need to pay the price.

Doug
Thank you sir....what I needed to hear.
 

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Or you could get a set of 496 take off manifolds that weight a lot less and flow better than stock 454/502 cast iron manifolds. I bought mine for $300....very economical upgrade.
 

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On a jet boat, I heard these rock. For some reason only jet guys are into these.

No, they DO NOT complete with the driver side deflector. Thats extra, but available at any Home Depot
That's called reverse ram air induction!! :happy:
 
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