Strip Dominator - Spread bore weld up

Hughes used to offer that operation on M1 manifolds(they still might).

One time I had a customers 452RB on the dyno and he had two of the M1’s to try.
One that was stock, the other had been welded up and blended to make it a regular square bore flange.
This was about a 600hp build.
The welded/blended one was worth about 4-5hp.
Both intakes were port matched.