Reply to "Blue Thunder intake manifold porting"

You have no experience with the Shelby manifold, yet you are convinced it requires "straightening out"? What if "straightening-out" the manifold involves cutting down the plenum divider, softening low rpm power, and reducing manifold vacuum? Will that be an acceptable trade-off for you? What if the same improvement in horsepower could be achieved by merely blocking the manifold's exhaust heat passage? Blocking the exhaust heat passage would not soften low rpm power or reduce manifold vacuum. The manifold is 40 years old, surely if there's a problem its would have been documented in a publication somewhere. Have you read the advice recommending this modification from more than one source? If the manifold were such a dog why would it be so well liked by old farts like me? Wouldn't it be wise to use the manifold as-is before you have it modified, so you can compare the performance before and after?

If you must have the manifold modified, I can recommend somebody who is a professional at doing that work. He's a guy pro-engine mechanics send their work to. The guy you're looking for isn't him.