FWIW I ran this past a Steward who has been in this game for a while.

He is of the opinion that as the manifold is listed as a seperate item, the intention of the Comp Board when they wrote the rule is very clear; you can not touch the inside of the manifold past the 1" point.

To call polishing "blueprinting" is going to be a very hard sell. The first thing the Stewards will ask for are the factory blueprints showing the designed interior configuration of the part. Got 'em?