Bearcamp,
If you're talking the holes in the megaphone you'll have to cut to fit, depending on how you want them to look. Instead of the "kit" I bought the megaphones from Speedway, and then bought seven or eight 1.625" J-tubes from Summit. Mine was a bit of a special case, as I did not want to cut my splash aprons, so I had to custom fit the primaries at decreasing angles to follow the megaphone angle. You can see mine in my build thread, about #57 Followed Me Home, '33 Build just for a point of reference.