ProComp/Speedmaster aluminum heads

Do you have to channel your rear (73&up)fiberglass bumper so it doesn't stick out on the sides to much?

Thank you great stuff!
From looking at your CNC ported Speedmasters (just eyeballing of course) would you say that they would by the looks of them flow a little better than a good port job on a stock head?

Eyeballing **** at my age does not work...let me see what I got in storage.....never know what might be hiding in a box...lol
The SM does not cnc the chamber....only the ports...