So I have my motor swap almost completed. My question is, how much will the factory v6 exhaust restrict the flow of my 97 Dohc motor? The motor is all stock Im just putting it in to make sure I have all the swap stuff done right and to put a coupe miles on it next spring. Is the stock 2.8 exhaust going to restrict the flow a substansual amount?

At low rpm, probably not.
But the engine is putting out almost 25% more gas per stroke based on simple displacement and it does rev to 9k.
So if the stock ex is good for say 6k from a 2.8, it's going to be good for maybe 4.5 k rpm on the dohc just based on simple math alone.
Will ir work, probably, wil it be ok? Only one way to find out. But if you've gone to the trouble of putting that motor in there, may as well do the whole job.
I think I built my ex from 2 1/4 inch pipe and u bends. Hardest part was finding a muffler that would fit in there.

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Anything I might say is probably worth what you paid for it, so treat it accordingly!

Dave

www.ltlfrari.com

I built up a 2.5" system with a Spintech crossflow muffler and stock Fiero tips. It flows like mad, but it's LOUD. Too loud for me, so I am considering putting the stock Fiero muffler in with the 2.5" pipes. I know it will be a bit of a bottle neck, but I need to keep my hearing.

I ran the stock muffler and tailpipes behind a small block Chevy (350) for a time. It sounded and ran great, but that engine never ran beyond 5000 RPM.

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1986 SE Aero coupe.

3.4 DOHC swap is complete and running, now just have to finish the rest of the car...

I think I'm just going to bite the bullet and but WCF 3" cat back system. I was just hoping to wait until the built motor goes in next winter to buy that exhaust.

I seem to recall I used a magnaflo muffler and I had a cat in there as well in the stock locaton, way too loud. In the end I put some CC inserts in the pipe between the cat and muffler. I am sure it did not help the flow any but it got the decibels down to a reasonable level and it still pulled like crazy so I don't think the inserts hurt it too much.

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Anything I might say is probably worth what you paid for it, so treat it accordingly!

Dave

www.ltlfrari.com