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Best option for 5.7 Mag exhaust replacment?

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Old 05-19-2010 | 10:31 AM
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Default Best option for 5.7 Mag exhaust replacment?

Hey Guys,

I've got a 1990 Scarab 21' with a 5.7 Mag. I've noticed a small crack in the water jacket of one of the exhaust manifolds, so I'm looking to replace the set. Does anyone have any experience with the cheap re-pops out there?

Thanks
-Rob
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Old 05-19-2010 | 07:49 PM
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try this...

http://www.perfprotech.com/store/pro...-NS,75402.aspx

i'd do the cheap manifolds, but go with imco or another quality ss riser...
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Old 05-19-2010 | 08:59 PM
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I just put the Imco Thumper setup on my boat.It was reasonable about 1k a motor and came with everything.
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Old 05-19-2010 | 10:36 PM
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I would take a look at Revolution marine exhaust.
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Old 05-20-2010 | 02:09 PM
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I have used GLM aluminum manifolds with very good results. The internal passages are a split design (separating the exhaust pulses) and the aluminum shaves about 50 lbs off the stern. I paired these these with a set of Hardin/IMCO stainless risers. Very good results... I have about $500 in the whole set up (I bought the risers used).

Tom
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Old 05-20-2010 | 05:19 PM
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tom z did you see any difference in performance with the glm manifolds. any gain in rpm. thanks.
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Old 05-20-2010 | 08:38 PM
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Thanks for the ideas guys!

I think I'm going to end up picking up some factory Merc manifolds.

I see 2 options, ceramic or E-coat.

Merc's site says Ceramic for salt, and E-coat for fresh, is this correct?

Thanks
-Rob
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Old 05-20-2010 | 11:08 PM
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Originally Posted by cigarette39
tom z did you see any difference in performance with the glm manifolds. any gain in rpm. thanks.
I couldn't tell you. I picked up the boat sans power and built a 383 for it. It was turning 5300-5400 RPM and running 77 on GPS. I have other friends with small block power running the same setup and approaching or surpassing 80. I'd say they work.

Dennis Moore (Small Block and Big Block Marine Performance book author) is behind the design on these.

I have a new cam from RMBuilder going in this weekend. Hoping to add another 800 RPM or so. The exhaust is more than capable of supporting it.

Hope this helps.

Tom
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Old 05-21-2010 | 12:25 AM
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thanks tomz let me know how the new cams work.
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