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LS3 EROD vs G8 LS3 exhaust manifold fit

Old 02-24-2019, 09:37 PM
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Smile LS3 EROD vs G8 LS3 exhaust manifold fit

I have a 1995 Miata with an LS1 in a V8Roadster setup and dinged Sanderson headers for steering shaft clearance. I am trying to make it CA smog legal with a OEM exhaust manifold or CA legal header and catalytic converters. Has anyone tried the OEM Pontiac G8 or LS3 manifolds with cats without moving the steering shaft? I am considering adding joints and an offset steering shaft if required.
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Old 03-08-2019, 11:15 AM
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I don't know if anyone has tried it, but can see your point. Food for thought....take a look at the 2009-2015 CTS-V setups. It is the same style but the cat is much smaller. I may even have a set laying around.
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Old 03-08-2019, 03:20 PM
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You might look over the CARB legal LS build that is around here somewhere.
As best I remember he utilized 2006 GTO exhaust manifolds and cats but I have slept several times since reading the thread.
Also going off memory, the fitment issue was not the steering shaft but rather the firewall.

I do know that the V8 Roadster subframe is different from the Monster subframe but I do remember reading several places where the Pontiac G8 manifolds will work with the Monster subframe.
Taylor Ray uploaded a series of YouTube videos where he did an LS build in his Miata and originally used G8 manifolds.
He has since switched them out in a search for more performance.
From looking at his engine placement compared to my car, it looks to me like the Monster subframe places the engine about 1"-2" further away from the firewall than the V8 Roadster subframe.
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