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Discussion Starter #1
What up


Just looking for opinions, I have a 454 mag 385 hp. What is the best all around exhaust for this motor,

There seems to be quite a selection for this motor. Only adding the exhaust. What is a good price as well I know I might have to increase the prop size, But do I have to recal the ecu unit as well

One last thing is the K&N filter worth the money I have seen in test that they claim 9 hp and an exhaust is about 50hp give or take

Thaks for the info in advance

Mark
"AKA "
MR HLB
 

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deckboat owner
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480 Posts
exhaust is pricey and reaps little benefit to a stock motor.
if the only other mod is a K & N you might think about saving your $$$
 

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The first mod you want to do on any Merc big block is get rid of the stock exhaust. You will pick up 200-300rpm's. You will not have to recal the ecu unit. Best bang for the buck is EMI Thunders.
 

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It's what we do
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723 Posts
I agree with Diamond. Good increases with exhaust. I would lean towards Imco Powerflow or Dana for best performance
 

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Broke mo fo
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Imco Powerflows. I put a set on my old 454 mag and it picked up a couple hundred rpm, and couple mph. The biggest gain I noticed though was the mid range acceleration.
 

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I put a set of EMI Thunder's on my last Nordic with a 300HP 454. Saw a two MPH increase. Put the same headers on a Nordic Rage with a 385HP 454 MPI Mag along with a K&N Flame arrester and saw no difference from stock. I guess it varies from boat to boat.
 

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Try to find a exhaust system (EMI, Stainless Marine etc.)that has a jumper hose from the manifold to the riser, a dry joint compare to a wet joint (Merc, IMCO)
 
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