It'll only be as good as the amount of time you take to do it.
Those are thee most involved casting of cylinder head for the these motors to get in shape to make good power.
Bolt on they are small bump in compression..but take a hit in air flow when compared to the other castings.
Watch the video and compare the as cast with the chamber work and valve job I did.
Both the chamber work and valve job are key to how they turned out to that point.
Your results will vary if you skimp on the detail/valve job.
