Nothing to do with magic. A 4.100 bore is FAR better than a 4.00 bore just like a 4.185 bore is FAR better than a 4.100 bore.
The bigger bore man’s you can run a bigger valve. As long as you have the port to feed it you’re golden.
And if you don’t use a bigger valve you unshroud the valve you have.
And a bigger bore makes more power.
Simple as that.
