Idk how much the gains would be but you should see these things. Looks like the manifolds off the little olds engines with small flange openings. The exhaust pipe itself is smaller than any ive seen even on a v6.
If anything the Olds V8 ports are too big, compare the aftermarket aluminum heads, they all have the floor raised and the ports shrunken. The diesel heads are no different, too big.If the head ports are tiny putting different exhaust manifolds and or headers wont do much of anything.
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