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Ok 91 turbo usdm does it have a 7 bolt exaust manifold or does it have a 9 bolt exaust manifold.Can I use a 9 bolt exaust manifold on a 7 bolt motor just wondering if this will work thinking of going bigger on the turbo and would like to know this info for a new manifold.Thanks for your help.
 

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91-92 use 7-bolt, a small portion of 93's use 7-bolt, the majority of 93's use 9-bolt, and 94-95 use 9-bolt. you can bolt a 9-bolt manifold on a 7-bolt head, or the other way around.
 

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To use the 9 bolt manifold for the use you intend to , you will need to have a machine shop drill and tap for the additional 2 studs for the extra support. Not having the additional studs would make it pointless to swap them out . The 9 bolt has a better design which adds vital clamping on both sides . It helps greatly on the drivers side where the manifold is known to leak . The 7 and 9 are interchangeable the only one which is not is the gen 3 . Also the manifold should hold as little of the turbos weight as possible the turbo should be braced . This is especially true with tubular manifolds which have a tendency to expand ,this can cause cracks or failure.
 

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Good luck finding a 9 bolt gasket. They arent made anymore.
 
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